Should they ask for their salaries to be increased like the salaries of their colleagues who are sponsored by the Association?
Question

                We are a group of preachers and knowledge seekers. We work as imams of masajid. We joined another preaching job from 7.30 to 13.30. We have other colleagues sponsored by the preaching association, they do the same job we do but their salaries are much higher than ours. We asked for our salaries to be increased to be equal or close to the salaries of our other colleagues, especially that every thing became expensive nowadays.  The association considers us salaried imams, although our salaries are not big. The association grants those sponsored by it extra money for property, while we get nothing considering that we have places to live within the masajid. Whether we take extra money for property or not, our salaries still are much less than other colleagues. Our annual leave is one month although our other colleagues have one month and half as an annual leave. Is it our right to ask the association to increase our salaries and annual leave just as our colleagues as we do the same work they do? Please answer our question. May Allah reward you!.
Praise be to Allah.
    If the matter is as described, and you do the exact same job 
    as your colleagues, then it is your right to ask for the same salary as 
    them, exactly the same regardless of whatever you are paid for other work, 
    because the employment contract is about working a certain number of hours 
    in return for certain wages, and outside of these hours he may do whatever 
    work he wants in return for payment or whatever, so long as that will not 
    affect his work in his regular job. 

    Treating employees fairly and reducing differences in their 
    salaries is the strong foundation for achieving success, spreading 
    tranquillity and removing resentment and grudges, especially if this is in 
    da’wah work which is undertaken by those who are expected to be good, 
    righteous and adhere to the limits of sharee’ah. 

    To sum up, you have the right to ask for your salaries to be 
    raised and to get the same time off as your colleagues at work are getting. 
    The association and those who are in charge of it should pay attention to 
    attaining fairness and reducing differences as much as possible, because 
    there is goodness, prosperity and success in that. 

    We ask Allaah to bless and guide us and you. 

    And Allaah knows best.