Sunan Ibn Majah, Book 21, Hadith 2791 (In-Book) ⓘ

It was narrated that Rifa'ah said: “I entered upon Mukhtar in his palace and he said: 'Jibril has just left me.' Nothing stopped me from striking his neck (i.e, killing him) but a Hadith that I heard from Sulaiman bin Surad, according to which the Prophet said: 'If a man trusts you with his life, then do not kill him.' That is what stopped me.”

حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا أَبُو لَيْلَى، عَنْ أَبِي عُكَّاشَةَ، عَنْ رِفَاعَةَ، قَالَ دَخَلْتُ عَلَى الْمُخْتَارِ فِي قَصْرِهِ فَقَالَ قَامَ جِبْرَائِيلُ مِنْ عِنْدِي السَّاعَةَ ‏.‏ فَمَا مَنَعَنِي مِنْ ضَرْبِ عُنُقِهِ إِلاَّ حَدِيثٌ سَمِعْتُهُ مِنْ سُلَيْمَانَ بْنِ صُرَدٍ عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ قَالَ ‏ "‏ إِذَا أَمِنَكَ الرَّجُلُ عَلَى دَمِهِ فَلاَ تَقْتُلْهُ ‏" ‏ ‏.‏ فَذَاكَ الَّذِي مَنَعَنِي مِنْهُ ‏.‏