A friend of mine made the intention to study Islam in another country and stay there forever. I gave him money but said that it was for his books and that he should not do anything else with it. He agreed. Some things went wrong and he came back after a few days. He used part of the money to get home. He is now again working in the country that I live in. Does he have to give back all the money that I gave to him before he left?
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
Since you set a condition that your friend spends the money that you gave him on buying books only, then this entails that this is a conditional gift. This means that the person to whom it was donated must comply with the condition because of the general saying of the Prophet : “Muslims must abide by their conditions in what is permissible.” [At-Tabaraani]
Also, Asna Al-Mataalib, which is one of the books of the Shaafi'i School of jurisprudence reads, about whoever donated a gift and conditioned that it be spent on something particular, “If a person gives someone else some money and tells him, ‘Buy a turban with it, or go to the public bath house, and so forth, then it is an obligation to spend the money on what the giver had specified, in consideration of his objective…”
Therefore, your friend must spend that money on what you have specified, and he is not entitled to spend it on other things.
If he does not spend the money on what you have specified to him, then he should give it back to you unless you agree to give it to him as a donation to spend it on whatever he wills.
Allaah knows best.
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