The Book of Oaths (Kitab Al-Aiman)

Muslim :: Book 15 : Hadith 4088

Abu Mas'ud al-Ansari reported: When I was beating my servant, I heard a voice behind me (saying): Abu Mas'ud, bear in mind Allah has more dominance over you than you have upon him. I turned and (found him) to be Allah's Messenger (may peace be upon him). I said: Allah's Messenger, I set him free for the sake of Allah. Thereupon he said: Had you not done that, (the gates of) Hell would have opened for you, or the fire would have burnt you.

Source materials are from the University of Southern California MSA site
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