It is narrated from Hazrat Zadhan that Hazrat Abdullah bin Umar (may Allah be pleased with them both) freed his slave, then picked up something from the ground and said, "There is not even as much reward for me as this." I heard the Holy Prophet (peace and blessings be upon him) say: "Whoever slaps his slave, its expiation is to set him free."

It is narrated from Hazrat Hilal bin Yasaf that an old man slapped his servant. Hazrat Suwaid bin Muqarrin said: "You have no option now except to set him free. I remember, we were seven sons of our father Muqarrin, and we had a female servant whom the youngest among us slapped, so the Holy Prophet (peace and blessings be upon him) ordered us to set her free."