Sahih al-Bukhari 121Book 3, Hadith 63
حَدَّثَنَا حَجَّاجٌ، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ أَخْبَرَنِي عَلِيُّ بْنُ مُدْرِكٍ، عَنْ أَبِي زُرْعَةَ، عَنْ جَرِيرٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ لَهُ فِي حَجَّةِ الْوَدَاعِ " اسْتَنْصِتِ النَّاسَ " فَقَالَ " لاَ تَرْجِعُوا بَعْدِي كُفَّارًا يَضْرِبُ بَعْضُكُمْ رِقَابَ بَعْضٍ ".
The Prophet (ﷺ) said to me during Hajjat-al-Wida`: Let the people keep quiet and listen. Then he said (addressing the people), "Do not (become infidels) revert to disbelief after me by striking the necks (cutting the throats) of one another (killing each other).