Zadhan Abl Umar reported:I came to Ibn 'Umar as he had granted freedom to a stave. He (the narrator further) said: He took hold of a wood or something like it from the earth and said: It (freedom of a slave) has not the reward evert equal to it, but the fact that I heard Allah's Messenger (way peace be upon him) say: He who slaps his slave or beats him, the expiation for it is that he should set him free
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