Is it considered theft to conceal part of the tip and not hand it over to the restaurant owner, and is it permissible to refuse to hand over the entire tip, especially given that the owner distributes it among all workers while the customer believes it is for the one who provided the service, and that the amount the waiter hands over to the owner is small?

The ruling on tips received by a restaurant waiter is detailed as follows:

1. What is taken as a gratuity and a kindness: The waiter owns it completely, and the restaurant owner has no right to it. This amount is often small and given to the poor or as encouragement, falling under the category of good deeds and kindness, not bribery. A number of contemporary jurists, including Sheikh Ibn Baz, Dr. Muhammad Al-Bahy, and العلامة Abd al-Rahman al-Barrak, and the Egyptian Dar al-Ifta, have issued fatwas permitting it. This becomes the waiter's private property upon receipt.

2. What is taken in exchange for what the worker is obligated to do: It is not permissible to take it, because the worker's benefits are owned by the restaurant owner. This falls under the category of favoritism and bribery, and may lead to negligence in serving other customers.

3. What is taken upon request from the waiter: This falls under the rulings of begging, and the general principle is that begging is forbidden except for the needy. The restaurant owner has the right to prohibit his workers from asking customers.

4. If the restaurant owner stipulates that no tips should be taken: The worker is not allowed to take it, because "Muslims are bound by their conditions," and the restaurant owner has the right to prohibit the worker from taking it or to acquire it, as the worker's benefits are owned by him.