What is the ruling on giving a tip to a plumber, carpenter, or telephone company employee after they have completed their task, whether they requested it or it was given to them without a request, given that they receive a monthly salary from their employer?

The currently common practice of tipping contains corrupting elements, among them: its prohibition if the worker receives a wage for his work, as mentioned in the Hadith of Ibn Al-Lutbiyyah. It also corrupts the worker's heart against those who do not tip, encourages him to beg, and may lead him to show favoritism towards the payer. Therefore, paying it is not permissible except in very narrow cases free from these corrupting elements, such as when the worker has finished his work and is not expected to perform any further work, in which case it would be considered an act of benevolence. The Permanent Committee, Al-Fawzan, and Al-Barrak have issued fatwas prohibiting it if it is in exchange for work, considering it a corrupting bribe.