Someone borrowed 2000 Syrian liras from me. Afterward, I donated 4000 liras to help him with the expenses of his severely ill father without him asking for assistance; I did not tell him this amount was a debt. Later, we differed and separated. Then, I asked him to repay the 2000-lira debt, yet he insisted on paying off the entire amount (6000 liras), saying it is due to me and that he does not want a favor from anyone. I firmly refused and told him that I only have right to the 2000 liras, not the rest of the amount, for it was not given as a debt. My question is, am I religiously permitted to accept the 4000 liras and spend it as I will? Can I donate this amount for a charitable cause, such as building a mosque?
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, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Scholars differed over the ruling on someone who gives charity to a certain person who does not accept it. Some held the view that such a person should still give that amount of money in charity to another poor person and refrain from using it. Some others were of the opinion that he may benefit from it.
Ad-Dusooqi, a Maaliki scholar, quoting Ibn Yunus, said that Maalik said:
"If you go out with a piece of bread or dirham to give to a certain person and you do not find him, I hold that you should give it to another poor person to complete the good act. Hence, it is more likely to give the second poor one who is eager to receive your charity."
There is difference over whether he may keep it for himself in either case. Some are of the opinion that he may not keep it at all; and others say he may in either case. Some others hold that if it was intended for a specific person, he may keep it; otherwise, he may not.
No doubt it is safer not to keep it and to give it as charity to other poor people or donate it for the construction of a mosque, as suggested by the questioner.
You can search for fatwa through many choices