Hilal bin Yasaf said: We were in the house of Sayyiduna Suwayd bin Muqarrin (may Allah be pleased with him) when a slave girl of his came out and said something to a man, I do not know what, and he slapped her. Sayyiduna Suwayd bin Muqarrin (may Allah be pleased with him) saw this and said: You struck her on the face! I have seen myself as the seventh of seven brothers, and we had only one servant. A man slapped him, and the Messenger of Allah (peace and blessings be upon him) ordered us to free him.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6422