Is an end-of-service bonus disbursed, given that the employer refuses to pay it, claiming that it is not mentioned in Sharia, and given that the worker has not received all of his annual leave?

If, at the time of signing the contract, an agreement was made regarding an end-of-service bonus, the employer is not permitted to withhold it, based on the Prophet Muhammad's (peace be upon him) saying: "Muslims are bound by their conditions, unless it is a condition that forbids what is lawful or permits what is unlawful." However, if the employer stipulated at the time of the contract that there would be no bonus, then there is no right to demand it. If no agreement was made regarding this, then if the company's regulations stipulate its disbursement, the employee has the right to demand it; otherwise, they do not.