Chapter 25: The Book of Gifts
Umar b. Khattab (Allah be pleased with him) reported: I donated a pedigree horse in the path of Allah. Its possessor made it languish. I thought that he would sell it at a cheap price. I asked Allah' s Messenger (ﷺ) about it, whereupon he said: Don' t buy it and do not get back your charity, for one who gets back the charity is like a dog who swallows its vomit.
Sahih Muslim 1620a