Sahih Muslim, 4299

Rapporté par Zadhan : Ibn ‘Umar a appelé son esclave et a vu des marques (de coups) sur son dos. Il lui a dit : « Je t’ai fait du mal. » Il a répondu : « Non. » Mais Ibn ‘Umar a dit : « Tu es libre. » Il a alors pris quelque chose du sol et a dit : « Je n’ai même pas de récompense équivalente à cela. J’ai entendu le Messager d’Allah ﷺ dire : “Celui qui frappe un esclave sans raison valable ou le gifle (sans faute grave), l’expiation est de l’affranchir.” »

Zadhan reported that Ibn Umar called his slave and he found the marks (of beating) upon his back. He said to him:I have caused you pain. He said: No. But he (Ibn Umar) said: You are free. He then took hold of something from the earth and said: There is no reward for me even to the weight equal to it. I heard Allah's Messenger (ﷺ) as saying: He who beats a slave without cognizable offence of his or slaps him (without any serious fault), then expiation for it is that he should set him free