It is narrated from Sayyiduna Umar (may Allah be pleased with him) that once I gave a horse to someone in the way of Allah for riding, but he wasted it. I thought of buying it back, because I thought he would sell it cheaply. But I consulted the Prophet (peace and blessings of Allah be upon him), so the Prophet (peace and blessings of Allah be upon him) said: Do not buy it, even if he gives it to you in exchange for money, because the example of one who takes back his charity is like a dog that vomits and then licks it up again.