Is it permissible to donate the amount that the debtor returned in excess of the debt, knowing that the lender did not consider the additional amount a debt from the beginning?

Scholars differed regarding the ruling on a charity (sadaqa) that was not accepted by the recipient. Some scholars held that it is obligatory to give it to another poor person and that the giver should not benefit from it. Others held that it is permissible to benefit from it. Al-Dasuqi reported from Ibn Yunus that Imam Malik held that the charity should be given to someone other than the initial solicitor if he is not found, or if he does not accept it after being found. They also differed on whether it is permissible for the giver to consume this charity or not. Some said it is absolutely impermissible, some said it is absolutely permissible, and some said it is permissible if the intended recipient was specifically designated, but not if he was not. The most cautious approach is to give it as charity to other poor people or to spend it on building a mosque.