It is narrated from Hazrat Aslam Adawi that I heard Sayyiduna Umar bin Khattab (may Allah be pleased with him) say: I gave a fine horse to a man in the way of Allah, but that man ruined it, so I intended to buy it back from him, and I thought he would sell it cheaply. So I asked the Messenger of Allah (peace and blessings be upon him), and he said: "Do not buy it, even if he gives it to you for one dirham, because the one who takes back his charity is like a dog that vomits and then eats its vomit."

It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that Sayyiduna Umar bin Khattab (may Allah be pleased with him) gave a horse in the way of Allah, then intended to buy it back, so he asked the Messenger of Allah (peace and blessings be upon him). The Prophet (peace and blessings be upon him) said: "Do not buy it, and do not take back charity."

Imam Malik (may Allah have mercy on him) was asked: A person gave charity, then found it being sold and it was with someone other than the one to whom he had given charity; should he buy it? He said: No, it is better not to buy it in my view.