Is it permissible for the one giving charity to ask the poor person for supplication in exchange for the charity?

A Muslim's request for his Muslim brother to supplicate for him is permissible. This includes a donor asking the recipient of charity to supplicate for him. Furthermore, the needy person or the recipient of charity is obliged to supplicate for the donor, even if not asked, based on the Prophet's (peace and blessings be upon him) saying: "Whoever does you a kindness, then repay him; and if you cannot find anything with which to repay him, then supplicate for him." Charity may also ward off and remove illnesses even without the supplication of the needy.