Sayyiduna Umar bin Khattab (may Allah be pleased with him) narrates: I gave a horse as charity in the way of Allah. The person who had the horse wasted it, so I intended to buy that horse back from him, thinking that I would be able to buy it for a low price. I asked the Prophet Muhammad (peace and blessings be upon him) about this, and he said: Do not buy it! Even if he gives it to you in exchange for one dirham, because the one who takes back his charity is like a dog that eats its own vomit.