It is narrated from Sayyiduna Abu Mas’ud (may Allah be pleased with him) that one day I was beating one of my slaves when I heard a voice from behind me three times, “O Abu Mas’ud! Remember!” I turned around and saw that it was the Prophet (peace and blessings of Allah be upon him). He (peace be upon him) said: “By Allah! You have as much power over this slave as Allah has more power over you.” At that very moment, I swore that I would never beat any slave again.