Development of thriving at work and organizational citizenship behavior through Islamic work ethics and humble leadership

This study examined the mediation and moderation models of the relationship between Islamic work ethics (IWE), thriving at work, organizational citizenship behavior (OCB), and leader humility. A total of 418 employees from two different sample groups (Islamic banks and educational institutions) in Indonesia were included. A multiple regression hierarchy with PROCESS was used to test the hypotheses. We found a positive influence of IWE and leader humility on thriving and OCB and thriving at work on OCB. Thriving was found to mediate the relationship between IWE and OCB, and the leader humility moderates these relationships. Thriving at work and OCB are dramatically under-represented in Islamic work ethics research, and this study attempts to fill this void. Furthermore, this study reveals the interactive role of leader humility and IWE in enhancing OCB preference and the mediating role of thriving at work in the IWE − OCB relationship.


Introduction
In the last 2 decades, the emergent concept of thriving at work has attracted management researchers. The concept of human thriving was initially used to describe human function and how humans develop and adapt to various situations (Brown et al., 2017). More specifically, thriving refers to the "joint experience of a sense of vitality and learning" (Porath et al., 2012: p. 250) experienced by a person in an environment. Regarding the context of the work environment, Kleine et al. (2019) identified thriving at work outcomes, including health (e.g., burnout), attitude (e.g., job satisfaction, turnover intention), and performance (e.g., organizational citizenship behavior and creativity). Due to its influence on various employee behaviors and attitudes, thriving at work is extremely important for companies in developing talent and employee health and well-being, as well as managing competitiveness (Pfeffer, 2010;Porath et al., 2012).
A prior study widely adopted by researchers is the socially embedded thriving model developed by Spreitzer et al. (2005). In this model, Spreitzer et al. identified two main factors of thriving at work: contextual and resources. They also added agentic behavior (task focus and exploration) to explain that individuals can be internally motivated to thrive in their work. Furthermore, they stated that thriving at work improves individual health and well-being (Spreitzer et al., 2005). Recently, two meta-analyses (i.e., Kleine et al., 2019;Liu et al., 2021) expanded Spreitzer et al.'s model by identifying the antecedents and consequences of thriving at work in a broader manner. Despite numerous studies identifying the predictors of employees' thriving at work, several concepts have not yet been identified. For example, Liu et al. (2021) identified five leadership models (empowering, servant, authentic, leader-member exchange (LMX), and transformational leadership) as sources of thriving and ignored the recently popular leadership model, namely leader humility. In contrast, in this study, we attempt to explore the antecedents of thriving at work from the perspective of spiritual/religious values, which have previously been positively related to thriving (Dowling et al., 2004;van der Walt, 2018;King et al., 2011aKing et al., , 2011b. This study explicitly proposes the concept of Islamic work ethics (IWE) as an Islamic-based work ethic value as an antecedent of thriving at work.
Islamic work ethics are ethics based on Islamic religious values. In contrast to ethics from the Western world (e.g., Protestant work ethics or PWE), which are more oriented toward economic achievement (Ali & Al-Owaihan, 2008), IWE is more balanced between faith and economic needs (Ali, 1988). In other words, IWE has an orientation that combines trust/belief with working to gain economic progress and wealth (Ali & Al-Owaihan, 2008;Suryani et al., 2021). Therefore, we attempt to fill a gap in the literature on thriving at work by exploring the role of IWE and leader humility among employees of Islamic banks and education institutions in Indonesia.
There are two reasons IWE is essential for organizations, especially in the Muslim community: first, work ethic values are typically derived from western society, based on their community values and beliefs; thus, IWE from other civilizations cannot be ignored (Ali & Al-Owaihan, 2008). Ali and Al-Owaihan (2008) articulate IWE as a combination of moral, economic, social, and psychological elements in viewing work activities. In other words, working from an Islamic perspective should simultaneously have individual and social benefits. In addition, IWE is fundamentally different from PWE or other conventional ethics. The measure of morality in the IWE is based on intentions (not on results), and business and economic activities must still be based on Islamic religious values. For example, prohibited business activities such as monopoly, gambling, drug trafficking, and trading in alcohol are considered immoral activities, even though they are economically profitable. Second, there is an excellent need for Muslim society to implement IWE in everyday life and work (Murtaza et al., 2016;Suryani et al., 2021). On the other hand, empirical evidence regarding the effect of IWE on individual and organizational behavior is still open. Hence, the present study provides insight for Muslim scholars and business practitioners regarding the importance of implementing IWE.
Specifically, the present study makes three significant theoretical contributions to thriving at work by exploring antecedents that have not been studied in existing research. First, our study uncovers the IWE as a potential predictor of thriving at work that did not previously exist within the academic literature. Although spiritual/ religious values have been studied previously (e.g., Dowling et al., 2004;van der Walt, 2018;King et al., 2011aKing et al., , 2011b, our study explicitly uses the IWE concept. Thus, besides helping expand the thriving at work model, this study also covers the dearth of knowledge regarding the consequences of IWE on human thriving, which existing studies had not previously explored (Ali and Al-Owaihan, 2008;Suryani et al., 2021).
Second, we add to the scarce research by considering leader humility as an antecedent of employees' thriving at work. We complement leadership studies (e.g., leader-member exchange, empowering, and transformational leadership) on thriving at work (Hildenbrand et al., 2018;Li et al., 2016;Lin et al., 2020;Nielsen & Marrone, 2018;Xu et al., 2019). In addition, the study contributes to a better understanding of thriving at work from a virtue-based perspective (e.g., IWE and leader humility); therefore, the combination of the two is interesting to examine.
Third, with the SET as the main framework and socially embedded model (Spreitzer et al., 2005), we integrate communal values as complementary to the agentic view. For example, a humble leader is a bottom-oriented leadership character (Owens et al., 2013;Rego et al., 2017) that can both create agentic orientations (task focus, exploration, and heedful relating) and encourage communal behavior (social bonds and corporation-oriented; Fung et al., 2016). Based on these considerations, we expand the socially embedded model by adding the consequences of IWE, leader humility, and thriving at work to organizational citizenship behavior (OCB) (see Fig. 1).

Literature review and hypotheses
This study is based on the framework of SET (Blau, 1964) and the socially embedded model (SEM) to explain the relationship between IWE, thriving at work, OCB, and leader humility. Both the SET and SEM focus on the quality of social  Homans (1961) focused on balancing economic and psychological needs as individual self-interests that drive exchange intensity. Exchange resources can be both material (e.g., financial rewards) and non-material (e.g., work climate, psychological environment), both of which are relevant to IWE (Suryani et al., 2021) and leader humility, which focuses on the quality of interaction. In contrast, SEM specifically suggested agentic behavior assumptions to explain that individuals can be internally motivated to thrive at their work. Agentic behavior refers to the motives of dominance and competence (Fung et al., 2016) that drive employees to thrive (Spreitzer et al., 2005). We suggest another alternative to explain the effect of IWE and leader humility on thriving and employees' extrarole, namely communal values, which better reflect the development of "cooperation and social bonds" (Fung et al., 2016, p. 274). In the context of OCB, individuals who are oriented toward communal behavior may be more motivated by a desire to increase cooperation and social bonds than by showing competence and dominance in an agentic context (Fung et al., 2016;Thrasher et al., 2020). Within the context of leader humility, the interplay between agentic and communal values has unique consequences for employees' positive behavior. For example, leader humility is believed to be a predictor of the collaborative environment (Owens & Hekman, 2012a, 2012b, team performance (Rego et al., 2017), psychological capital (Qian et al., 2020), promotion of employees' knowledge-sharing behavior (Anand et al., 2019;Nguyen et al., 2020), and team humility (Ye et al., 2020). Accordingly, leader humility is the basis for driving agentic (dominance and competence) and communal behaviors (cooperation and social bonds).

IWE and thriving at work
IWE are a set of principles and guidelines derived from the Quran and Sunnah of the Prophet Muhammad PBUH. Since it was first introduced by Ali et al. (1988), IWE has attracted much attention from Muslim researchers because of its positive impact on individual and organizational behavior. IWE has four main principles of "effort, competition, transparency, and morally responsible conduct" (Ali & Al-Kazemi, 2007, p.95), which can be applied in everyday life and work (Suryani et al., 2021). For example, IWE is considered a significant predictor of managerial effectiveness (Javed et al., 2020) and individual behavior, including creativity, innovative behavior, cooperation, organizational commitment, job satisfaction competitiveness, OCB, and knowledge-sharing behavior (Ali and Al-Kazemi, 2007;Kumar & Che Rose, 2010Murtaza et al., 2016;Nasution & Rafiki, 2020;Salahudin et al., 2016;Suryani et al., 2021;Yousef, 2000). Although it has attracted the attention of many researchers in the last 2 decades, there are many areas of study that have not been explored, including its relationship with thriving at work.
From an organizational behavior perspective, Spreitzer et al. (2005) defined thriving as a psychological state that combines vitality and learning. Vitality refers to an emotional state characterized by high enthusiasm, energy, and enthusiasm for work. The concept of vitality has similarities with the sub-dimension of "vigor" of work engagement (Schaufeli et al., 2002(Schaufeli et al., , 2006. Learning refers to how individuals acquire and apply new knowledge to build their abilities and self-confidence . Thus, individuals who experience thriving at work always feel full of energy and great enthusiasm (vitality) and feel that they have new experiences and knowledge (learning). In line with the ever-evolving human perspective, thriving was also found to be an essential factor for individual health, performance, life satisfaction, and well-being (Kleine et al., 2019;Porath et al., 2012;Zhai et al., 2020).
This study employs the SET (Blau, 1964;Homans, 1961) to explain the possible relationship between IWE and thriving at work. Based on the SET, resources can be tangible and intangible, or economic and psychological (Blau, 1964;Homans, 1961), and IWE contains both kinds of resources. For example, IWE specifically regulates wages in financial terms based on justice, feasibility, and clarity. In this context, justice refers to the balance between work and wages. Feasibility refers to the consideration of suitability for life needs. Finally, clarity refers to the existence of an "akad," which is an agreement between the employer and the recipient of the work (Basyir, 1996;Syafei, 2001). On the intangible side, IWE is a set of values that promote positive interactions between employees and colleagues, superiors, and subordinates (Ali, 2005). In line with SET, which prioritizes the quality of interaction through "equilibration, expectancy and distributive justice in dyadic exchange" (Homans, 1961), the application of the four IWE principles can directly encourage vitality through effort and competition and learning through knowledge-sharing behavior (Murtaza et al., 2016;Suryani et al., 2021). Furthermore, religious and spiritual values have been positively related to thriving (Dowling et al., 2004;van der Walt, 2018;King et al., 2011aKing et al., , 2011b. Based on these arguments, we hypothesize the following: Hypothesis 1. Islamic work ethics are positively related to thriving at work.

IWE and OCB
IWE are guidelines for individual and organizational behavior as a whole that prioritize four main elements, namely effort, competition, transparency, and morally responsible conduct (Ali, 2005;Ali & Al-Owaihan, 2008). Furthermore, IWE focuses on encouraging individuals to work hard and getting good results in return, which can create intrinsic motivation (Gheitani et al., 2019); as stated in the Quran, "Give a full measure when you measure out and weigh with a fair balance" (Quran 27: p. 9). Additionally, IWE encourages knowledge-sharing behavior, as stated by the Prophet Muhammad PBUH, which states that humans have three primary wills, namely being an obedient son, giving charity, and helping others, and knowledge that is beneficial to society (Gheitani et al., 2019;Hamid, 2011;Kumar & Che Rose, 2010). In this context, it is apparent that Islamic teachings encourage humans to help each other in goodness, including in the workplace.
As an extra-role behavior, OCB has been used to categorize employees who voluntarily devote their energy and time to helping colleagues and the organization without expecting special rewards. Organ (1988) defined OCB as a discretionary behavior that can increase the effectiveness of individual and group functions. Individuals with a high OCB tend to volunteer to help their colleagues without expecting formal rewards from the organization (Posdakoff & Mackenzie, 1994, p. 351). According to SET, OCB is a condition in which individuals are willing to sacrifice their time and energy voluntarily to fulfill social needs rather than economic ones (financial rewards). Similarly, IWE emphasize working as a balance between economic and social fulfillment. Islam encourages its followers to perform good deeds (e.g., helping others, sharing knowledge) and return goodwill (Murtaza et al., 2016). Furthermore, recent studies have provided initial support for the association between IWE and OCB (Ahmad et al., 2019;Murtaza et al., 2016;Tufail et al., 2017); thus, we also expect a positive effect of IWE on OCB.
Hypothesis 2. Islamic work ethics are positively related to OCB.

Thriving at work and OCB
OCB is a form of prosocial behavior in which the perpetrator does not expect specific rewards. Kleine et al. (2019) described the logic underlying this relationship as follows: when employees gain knowledge and assistance from the company, they will also be prepared to do the same to the organization through prosocial behavior. In the same context, when individuals acquire high vitality (vigor and enthusiasm), they give back to the organization and co-workers through civic behavior (Kabat-Farr & Cortina, 2017). Furthermore, individuals who attain vitality and learning in the workplace have an excellent opportunity to engage in citizenship behavior as part of reciprocation, according to the SET and agentic view (Kabat-Farr & Cortina, 2017;Kleine et al., 2019;Li et al., 2016;Marchiondo et al., 2018). Thus, we also propose a positive relationship between thriving at work and OCB.
Hypothesis 3. Thriving at work is positively related to OCB.

Mediating role of thriving at work
The mediating role of thriving has been confirmed in various research models. Recently, a meta-analysis by Kleine et al. (2019) classified antecedents into two groups: individual factors (e.g., psychological capital, core self-evaluation, proactive personality) and relational resources (e.g., workplace civility, supportive climate, and empowering leadership). Furthermore, the consequences of thriving at work were grouped into health, attitude, and performance. Li et al. (2016) confirmed thriving mediates the empowering leadership and OCB relationship. Using the arguments in H1 and H3, our study proposes that the relationship between perceived IWE predicting employee OCB and thriving at work is the underlying mechanism that explains this relationship. Thus, IWE can promote thriving at work,

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Development of thriving at work and organizational citizenship… and employees at a high level of thriving will engage in citizenship behavior in the workplace.
Hypothesis 4. Thriving at work mediates the relationship between IWE and OCB.

Leader humility, thriving, and OCB
Leader humility is a virtue-based leadership model that has received considerable attention from researchers in management and organizational behavior. Argandona (2015) explains that the main characteristics of a humble leader are openness to the ideas and opinions of subordinates, acknowledging achievements (e.g., giving verbal rewards and acknowledging subordinates' achievements), acknowledging their weaknesses, and willingness to share experiences with subordinates (Argandona, 2015). Therefore, leader humility is closely related to the formation of employee knowledge through their willingness to train subordinates (Nguyen et al., 2020) and creating a collaborative environment (Owens & Hekman, 2012a, 2012b. Although researchers have actively studied the consequences of leader humility on individual and group behavior, its impact on thriving at work has been relatively neglected. Previous studies have primarily used other leadership models to explore thriving at work (i.e., Hildenbrand et al., 2018;Li et al., 2016;Lin et al., 2020;Niessen et al., 2017;Xu et al., 2019), including leader-member exchange leadership (Xu et al., 2019), empowering leadership (Li et al., 2016), and transformational leadership (Hildenbrand et al., 2018;Lin et al., 2020;Niessen et al., 2017).
Drawing on SET, we argue that a humble leader can evoke or trigger employees' thriving at work through effective interactions with subordinates. For example, the behavior of a humble leader who is willing to share experiences, accept ideas, provide feedback, and train subordinates can directly improve employees' learning experience. Furthermore, a humble leader who focuses on ethics provides moral encouragement, rewards, and recognition for achievements that can stimulate intrinsic motivation and increase employee enthusiasm and work engagement (Li et al., 2021;Nielsen & Marrone, 2018;Owens et al., 2013;Sousa & van Dierendonck, 2017). Hence, we propose that the various types of support provided by a humble leader can affect the two main components of thriving at work (learning and vitality) simultaneously. Thus, the proposed hypothesis is as follows: Hypothesis 5. Leader humility was positively correlated with thriving at work.
A humble leader has great concern for developing the capacities of subordinates, including taking time to discuss and share their experiences (Owens et al., 2013). According to SET, the behavior of leaders who are willing to train and develop skills is transmitted to subordinates. Consequently, employees tend to spend time on tasks outside their responsibilities. In other words, using the exchange assumption in SET, employees who receive many favors from their boss tend to do the same thing for their colleagues in the form of OCB . For example, leader behavior that is open to subordinates' ideas and inputs can encourage employee voices (Ma et al., 2020;Qian et al., 2020) and knowledge-sharing (Anand et al., 2019). Similarly, as OCB is a discretional behavior, employees' actions to help co-workers can be motivated by a communal orientation that aims to create cooperation and social bonds (Fung et al., 2016, p. 274). Within leader humility, various forms of support provided by leadership have been confirmed regarding OCB (Nielsen & Marrone, 2018;Tuan et al., 2021). Accordingly, we propose the following hypothesis: Hypothesis 6. Leader humility has a positive influence on OCB.

The moderating role of leader humility
In addition to testing leader humility as a predictor of thriving at work and OCB, we also propose the role of a humble leader as a boundary condition in the IWE-OCB and thriving at work − OCB relationships. Therefore, the potential of leader humility as a moderator of IWE, thriving at work, and OCB relationship should be explored to expand the role of leader humility as a boundary condition. Although relatively limited and in different contexts, prior research has demonstrated the role of leader humility in the relationship between overqualification and career identity (Ma et al., 2020), as well as relationships between authority, trustworthiness, and compliance (Chiu & Hung, 2020). In this study, we expand on the role of leader humility in the relationships between IWE, thriving at work, and OCB.
Using SET's social penetration perspective (Altman & Taylor, 1973), effective social interactions between leaders and subordinates can influence employees' positive attitudes and behaviors. According to Chiu et al. (2016), an essential component of leaders' humility is how they build interaction patterns, thus providing support for subordinates' abilities and strengths (Chiu et al., 2016). Humble leaders do not hesitate to intervene directly to help work in the field and provide mentoring to solve problems and strengthen thriving in learning. Referring to the role of humble leaders in increasing employee capacity through discussion and feedback, we argue that this situation strengthens IWE's relationship with thriving at work. In other words, the combined effect of IWE and leader humility is ideal for increasing employee thriving. Thus, our proposed hypothesis is as follows: Hypothesis 7. Leader humility moderates the relationship between IWE and thriving at work.
Leader humility may also play a role in the thriving at work and OCB relationship. Since thriving at work has been validated as a predictor of OCB (e.g., Kabat-Farr & Cortina, 2017;Li et al., 2016), this relationship can be strengthened by the character of a humble leader who is oriented toward increasing collaboration and creating a dynamic work environment. Using the agentic and communal principle, a humble leader plays a role in encouraging the learning experiences of subordinates and, at the same time, increasing the communal value, where employees are given a role model to strengthen social bonds and cooperation (Fung et al., 2016). Thus, it is logical that high thriving at work and high perceived leader humility can encourage higher OCB. Thus, employees' OCB, formed by thriving at work, will be more vigorous when they perceive high levels of humility in their leader, hence the following hypothesis: Hypothesis 8. Leader humility moderates the relationship between thriving at work and OCB.

Sample and procedure
This study is an extension of a previous study (see Suryani et al. (2021) for a review) that examined the role of IWE on the behavior of Islamic banking employees in Indonesia. The first sample group is representative of three groups of Indonesian Islamic banks (BSI) located in three provinces: Jakarta, West Java, and Banten. A total of 396 respondents involved in the previous study were recruited again to answer questions about thriving at work and OCB; of these 396 respondents, only around 57.10% (227 participants) answered the questions for this study. Furthermore, we expanded the sampling area to the education sector to include six Islamic universities in Indonesia. The respondent group consisted of staff employees who were asked to answer questions on biographical information, Islamic work ethics, and leader humility in the first phase. Two weeks later, the respondents were invited back to answer questions about thriving at work and OCB. The total number of respondents involved was 418, consisting of 227 in sample group 1 and 191 in sample group 2. Table 1 displays the respondents' characteristics. Of the participants, 45.31% were employees of Islamic banking institutions, and 45.69% were from Islamic educational institutions. A total of 57.18% of the respondents were women, and the majority had a bachelor's degree or a diploma (41.87% and 38.52%, respectively). Forty-two of the participants had less than 2 years of service, 39.95% had worked in the company for 2-5 years, and the remaining 17.70% had worked there for more than 5 years. Finally, the average age of the respondents was 29.2 years, and 55.74% were married.

Measurements
All measurements were performed by adapting a scale developed in a previous study (Ali, 1988(Ali, , 2005Lee & Allen, 2002;Owens & Hekman, 2012a, 2012bPorath et al., 2012). Since all scales in our study were originally in the English version, we translated these scales into Indonesian using back translation procedures (Brislin, 1980). Some items were made with minor changes based on the advice of three researchers in the field of organizational behavior in the Indonesian version. All items were rated using a 5-point Likert type according to context (1 = strongly disagree/never, 5 = strongly agree/always).
We measured IWE using the scale developed by Ali (1988). Previous IWE researchers have widely used this scale (e.g., Ali & Al-Kazemi, 2007;Kumar & Che Rose, 2010). Sample items included "laziness is a vice" and "good work benefits both oneself and others" (Ali, 1988). Internal consistency based on the Cronbach alpha coefficient of 0.91 has met the requirements (Nunnally & Bernstein, 1994). A 10-item questionnaire was used to measure thriving at work (Porath et al., 2012). Sample items included "while working, I feel alive and vital" and "This work makes me have energy and spirit" (Porath et al., 2012). The Cronbach was 0.88. Leader humility was measured using a 9-item scale (Owens & Hekman, 2012a, 2012bOwens et al., 2016). Sample items included "My supervisor's appreciation of others' strengths" and "My supervisor's willingness to view oneself accurately." The internal consistency α of the scale was 0.89. Finally, OCB was measured using the 8-item organizational citizenship behavior individual (OCBI) sub-scale in Lee and Allen's (2002) study. Sample items included "Assist my supervisor with his/her work" and "Take time to listen to my coworkers' problems and worries" (Lee & Allen, 2002). The internal consistency α for this scale was 0.70.

Assessment of common method variance and confirmatory factor analysis
Because the data comes from one source (employees), it is possible to be exposed to the problem of common method bias (Podsakoff et al., 2012). We use several strategies to minimize this problem. First, the online questionnaire is designed to be anonymous to ensure respondent objectivity. Respondents participated voluntarily and were not given incentives. Second, we added another variable not included in this study and used time-lag data collection to create psychological separation to prevent respondents from inferring cause-and-effect relationships among the constructs (Iqbal et al., 2020;Podsakoff et al., 2012). Third, we applied two analytical procedures that were carried out using statistical methods: Harman's single-factor method and the collinearity assessment method using partial least square-structural equation modeling (PLS-SEM) as recommended by Kock (2017). The results for a single factor produced four factors with a cumulative variance of 58%. There was no dominant factor (> 50%), indicating that the data used in this study did not present serious problems of common method bias (Podsakoff et al., 2003). Furthermore, the full collinearity assessment by placing all constructs as endogenous alternately showed no items had a variance inflation factor (VIF) > 3.3, thus no serious common method variance (CMV) threat in the data (Kock, 2017). Table 2 presents the final results of the measurement model assessment after eliminating two items, namely item 13 from the IWE scale and item 10 from the thriving at work scale. All factor loadings exceeded the cutoff value of 0.50, composite reliability (CR) > 0.70, and average variance extracted (AVE) > 0.50, confirming that the measurement model had adequate construct validity (Hair et al., 2017;Sarstedt et al., 2014).

Hypothesis-testing procedure
We used serial moderated mediation analysis to test our hypotheses using PROCESS macro v.4.0 developed by Hayes (2017). The data were analyzed in three stages: in the first stage, the entire sample was analyzed (N = 418), and in the next stage (2-3), the samples from Islamic banks (n = 227) and Islamic educational institutions (n = 191) were analyzed separately. The 58 macroprocess model was used to test the mediation moderation model (Hayes, 2017).

Results and discussion
Correlation and descriptive statistics Table 3 presents the means, standard deviations (SD), and correlations between the variables in this study. As expected, the results showed that IWE is significantly positively related to thriving at work (r = 0.31, p < 0.01) and OCB (r = 0.39, p < 0.01). Moreover, thriving was positively related to OCB (r = 0.31, p < 0.01) and was also significantly related to leader humility (r = 0.28, p < 0.01).

Hypothesis-testing
Tables 4 and 5 show all hypothesis-testing in this study. First, IWE was positively associated with thriving for the entire sample (β = 0.29, p < 0.01), for the Islamic banking group (β = 0.25, p < 0.01), and for Islamic educational institutions (β = 0.34, p < 0.01). Second, IWE was also positively related to OCB, and this hypothesis is supported (β = 0.31, p < 0.01) for the combined sample, Islamic banks (β = 0.28, p < 0.01), and Islamic educational institutions (β = 0.34, p < 0.01). Third, thriving at work is positively related to OCB, and this hypothesis is also supported (β = 0.21, p < 0.01) for the combined group, Islamic banks (β = 0.17, p < 0.01), and Islamic educational institutions (β = 0.28, p < 0.01). As shown in Table 5, the indirect effect of thriving at work was positive and significant (β = 0.06, LLCI = 0.03, ULCI = 0.10) for the combined group (β = 0.04, LLCI = 0.00, ULCI = 0.09), Islamic banks, and Islamic educational institutions (β = 0.10, LLCI = 0.03, ULCI = 0.17). Overall, H4 was supported through 5000 bootstrap samples to determine the confidence intervals (CIs) for all significance tests (Cahyadi et al., 2021). H5 stated the positive effect of leader humility on thriving at work, and this hypothesis is supported (β = 0.19, p < 0.01) for the combined group, Islamic banks (β = 0.19, p < 0.01), and Islamic educational institutions (β = 0.18, p < 0.01). Leader humility was also shown to be positively and significantly related to OCB for the combined sample (β = 0.15, p < 0.01) as well as for Islamic banks (β = 0.15, p < 0.05) and Islamic educational institutions (β = 0.17, p < 0.01). Thus, H5 and H6 are supported. Hypotheses H7 and H8 stated the moderating effect of leader humility. As Table 3 shows, the interaction of leader humility and IWE revealed a positive and significant parameter (β = 0.23, p < 0.05) for the combined sample, Islamic banks (β = 0.23, p < 0.01), and Islamic educational institutions (β = 0.24, p < 0.01). Consistent with H5, leader humility also moderated the relationship between thriving at work and OCB. Table 4 shows that the interaction between leader humility and thriving at work had a positive and significant parameter for the entire sample (β = 0.20, p < 0.01) and the Islamic banking group (β = 0.21, p < 0.05). However, the leader humility × thriving at work interaction was insignificant for Islamic educational institutions (β = 0.13, p > 0.05). Hence, H7 and H8 are partially supported. The conditional effects of IWE on thriving at work and of thriving at work on OCB at values of leader humility and their interaction plots are shown in Figs. 2 and 3.

Discussion
Prior studies on thriving at work have recognized that religious/spiritual values are positively related to thriving (Dowling et al., 2004;van der Walt, 2018;King et al., 2011aKing et al., , 2011b; however, the concept of IWE in particular has not been explored in this regard. As IWE has been found to be a predictor of OCB (Ahmad et al., 2019;Murtaza et al., 2016;Tufail et al., 2017), we expanded this relationship by examining the role of leader humility as a moderator in the IWEthriving at work relationship. To our knowledge, no study has examined leader humility in the IWE-OCB and thriving at work-OCB relationships. Drawing on the SET and prior studies, we conceptually argued that examining the combined and interaction effects of IWE and leader humility on thriving at work and OCB can offer genuine insights into the existing literature.

Theoretical implications
First, the present study contributes to the Islamic work ethics literature by providing empirical evidence on how IWE affects employee thriving and OCB among Islamic bank and education employees. Drawing on the SET, the results showed that IWE can be used as a precursor for thriving at work. Indeed, researchers have generally shown that spiritual values are related to employees' thriving (e.g., Dowling et al., 2004;van der Walt, 2018;King et al., 2011aKing et al., , 2011b. We specifically used the concept of Islamic values. Since organizational citizenship behavior and thriving at work are dramatically under-represented in Islamic work ethics research, this study attempts to fill that void. Our study also aims to fulfill academics' calls to explore more broadly the effects of IWE on individual and group behavior in modern organizational contexts (Ali & Al-Owaihan, 2008;Suryani et al., 2021).
Second, our study also found a positive association between thriving and OCB. Moreover, thriving at work has also been shown to have an intermediate relationship between IWE and OCB. This study supports previous research (Alikaj et al., 2021;Kabat-Farr & Cortina, 2017;Li et al., 2016) and is the first to examine its role as a mediator in the IWE-OCB relationship. Thriving at work seems relevant in the context of IWE and OCB, as well as providing an alternative explanation of the IWE − OCB relationship process model. Third, we found a positive effect of leader humility on thriving and OCB. Our study complements leadership studies (e.g., leader-member exchange, empowering, and transformational leadership) on employee thriving both for Islamic banking and education samples (Hildenbrand et al., 2018;Li et al., 2016;Lin et al., 2020;Niessen et al., 2017;Xu et al., 2019). Most importantly, our findings also extend the socially embedded model of Spreitzer et al. (2005) in explaining the antecedents and outcomes of thriving at work. We integrated a communal orientation perspective as an alternative to explain thriving at work and OCB through leader humility. Using the SET perspective as the main framework, the character of agentic behavior (Spreitzer et al., 2005) may be enriched with communal behavior characteristics that are more social bondand corporation-oriented (Fung et al., 2016), thus providing an alternative explanation regarding leader humility, thriving at work, and the OCB relationship model.
Finally, our results regarding the role of leader humility moderate the relationship between IWE and thriving, and also, the link of thriving-OCB (see Table 6); these findings prove that leader humility plays a vital role in the two hypothesized relationships. It can be stated that the higher the levels of leader humility, the effect of IWE on thriving at work dramatically increases. In contrast, at lower levels of leader humility, the effect of IWE on thriving at work is drastically reduced and insignificant. In the same vein, leader humility also plays a vital role in the thriving at work and OCB relationship, where the effect of thriving at work on OCB is significant and positive for average and high levels of leader humility and insignificant when leader humility is at a low level. Thus, although IWE promotes thriving at work and thriving at work promotes OCB, the strength of these relationships largely depends on perceived leader humility, presumably because employees might have meaningful experiences in learning and vitality through leader behaviors that promote skill development, provide feedback on learning experiences (Argandona, 2015;Nguyen et al., 2020), and acknowledge subordinates' achievements, as well as through collaborative environments that trigger intrinsic motivation and enthusiasm (Owens & Hekman, 2012a, 2012b. However, contrary to our expectations, the moderating role of leader humility on the relationship between thriving at work and OCB is only significant for the accumulated sample and Islamic banks and not for Islamic educational institutions. Referring to Table 5, the effect of thriving at work on OCB is more substantial in the Islamic education sample (b = 0.28) than in the Islamic banks sample (b = 0.17). Thus, without being supported by a humble leader, OCB is effectively formed by thriving at work. This finding might be helpful for future studies to test the role of leader humility in the relationship between thriving at work and OCB in other samples, preferably in a different sector or organizational context.

Practical implications
Practical suggestions for management based on the findings of this study are as follows. First, as IWE play an essential role in encouraging thriving at work and OCB, managements need to consider broadly implementing IWE values in management practice. Apparently, in Islamic institutions (e.g., Islamic banking and education), managements need to strengthen the application of IWE by integrating them into organizational values (company code of ethics). Second, organizations can increase thriving at work and OCB through the practice of a humble leader. In this sense, managements must develop humble leadership capacity at the supervisor and manager levels. They must be trained to pay great attention to human resource development by providing feedback, encouraging two-way discussions, accepting input and ideas, being willing to listen to subordinates' complaints, and appreciating subordinates' contributions. Finally, IWE and leader humility are perfect for increasing thriving at work and OCB. It can be said that the implementation of IWE supported 1 3 by a humble leader seems suitable for improving the learning climate and employee vitality, as well as the effect on OCB.

Limitations
Apart from the theoretical implications of this study, several limitations deserve the attention of future researchers. First, we used self-report questionnaires for all variables with a potential common method bias in the data used in this study (Podsakoff et al., 2012). We attempted to address these concerns using several interventions based on the recommendations of previous studies. For example, we separated the measurement of the independent and dependent variables to create a psychological separation, which prevented respondents from connecting the variables (Podsakoff et al., 2012;Tehseen et al., 2017). In addition, we reduced concerns about CMV using two statistical tests, namely Harman's single-factor test and the full collinearity assessment method using PLS-SEM (Kock, 2017;Kock et al., 2021). Second, this study used two different sample groups using a time-lag approach. In addition to minimizing CMV (Tehseen et al., 2017), the time-lag approach is helpful in testing mediation models (Law et al., 2016). However, we suggest that future studies use a longitudinal design as a more accurate method to ascertain causality between variables.