Praise be to Allah.

The shar‘i ruling is connected to the manager whose job it is to supervise the work and how it is running: 

If the manager is appointed by the owners of the company and entrusted with the task of running and organising the work in such a way that will give the best results, then you can ask him and seek his permission with regard to the way of dividing up the night shift among the maintenance team, in such a way that everyone will be able to rest and sleep without that affecting his work or leading to any shortcomings. Then if he allows you to do that, there is nothing wrong with it. 

But if the manager has no authority in that regard, or there are strict instructions from the factory owners, in the sense that you know that no one has the authority to allow you to sleep during the night shift, or there is the possibility of trouble occurring in the factory and affecting production as a result of some people sleeping, and there is no way of undoing any harm that results, or if all employees remaining awake all the time will serve an extra interest for the work, then it is not permissible for you to go against what has been agreed upon, and you, as head of the team, must make everyone adhere to this shar‘i ruling. The employee in a company or organisation is described by the fuqaha’ as “one who is hired for a specific purpose” which means that he is doing specific work for a specific person on a temporary basis, and therefore he deserves his wages in return for making himself available during the agreed upon period to do that work. So he must commit himself to doing the work in the manner agreed upon, because the work he does is the right of the one who hired him – which in this case refers to the factory – to work during regular work hours throughout the years during which the worker is employed there. 

Al-Mirdaawi (may Allah have mercy on him) said in al-Insaaf (6/66): 

The “one who is hired for a specific purpose” hires himself out for a known period, during which the one who hired him is entitled to his work throughout that time. End quote. 

As it is the case that during work hours, the business owner has the right to his work, the worker has no right to delegate some hours to someone else or let someone else take his place, because this time is not his own. 

Similarly, the right of the business owner applies to every single employee who is working for him. Therefore no employee has the right to let someone else take his place on his own initiative. 

Al-Bahooti (may Allah have mercy on him) said: 

If the contract has to do with a particular person during a particular period, such as if he hired a specific person to do some sewing for him for a month, or to build a wall for him, then the worker got sick, no one else can take his place, because the contract applies to a specific person. This is like when one buys a specific item. 

End quote from Kashshaaf al-Qinaa‘ (4/31) 

See: Qawaa‘id al-Ahkaam by al-‘Izz ibn ‘Abd as-Salaam (2/185); Radd al-Muhtaar ma‘a ad-Durr al-Mukhtaar (6/70); Haashiyat ad-Dasooqi ma‘a ash-Sharh al-Kabeer (4/23); Mughni al-Muhtaaj (3/477) 

This ruling was previously discussed very briefly on our website; please see the answer to question no. 40509 

And Allah knows best.