(90) بَابُ أَدَبِ الْخَادِمِ
Abu Mas'ud said, "I was beating a slave of mine when I heard avoice behind me, 'Know, Abu Mas'ud, that Allah is able to call you to accountfor this slave.' I turned around and there was the Messenger of Allah,may Allah bless him and grant him peace. I said, 'Messenger of Allah, heis free for the sake of Allah!' He said, 'If you had not done that, theFire would have touched you (or the Fire would have burned you).'"
Reference: Al-Adab Al-Mufrad 171
In-book reference: Book 9, Hadith 16
English translation: Book 9, Hadith 171