Sahih Muslim, 4165

Zaid b. Aslam reported on the authority of his father that 'Umar (Allah be pleased with him) donated a horse in the path of Allah. He found that it had languished in the hand of its possessor, and he was a man of meagre resources He (Hadrat 'Umar) intended to buy it. He came to Allah's Messenger (ﷺ) and made a mention of that to him, whereupon he said:Don't buy that even if you get it for a dirham for he who gets back the charity is like a dog which swallows its vomit

Rapporté par Zaid b. Aslam d’après son père : Omar رضي الله عنه a donné un cheval dans le sentier d’Allah. Il a constaté que le cheval était négligé par son nouveau propriétaire, qui était pauvre. Omar a voulu le racheter. Il en a parlé au Messager d’Allah ﷺ, qui lui a dit : « Ne l’achète pas, même si tu l’obtiens pour un dirham, car celui qui reprend son aumône est comme un chien qui avale son vomi. »