Hilal bin Yasaf said: We were guests in the house of Sayyiduna Suwayd bin Muqarrin (may Allah be pleased with him). Meanwhile there was an old man, in whom there was sharpness of temper and ignorance, with a slave girl of his, and he slapped her on the face. I never saw Suwayd (may Allah be pleased with him) angrier than he was that day. Then he said: Could you find nothing but the tender part of her face? I have seen myself as the seventh of seven brothers of Banu Muqarrin, and we had only one servant. The youngest of us slapped her on the face, and the Messenger of Allah (peace and blessings be upon him) ordered us to free her.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6421