سنن أبي داود

Hilal b. Yasaf said : We were staying in the house of Suwaid b. Muqarrin. There was among us an old man who was hot-tempered. He had a slave-girl with him. He gave a slap on her face. I never saw Suwaid more angry than on that day. He said: there is no alternative for you except to free her. I was the seventh child in order of Muqarrin and we had only a female servant. The youngest of us gave a slap on her face. The prophet (May peace be upon him) commanded us to set her free.