Sahih al-Bukhari 7077
Sahih al-Bukhari · Book 92: Afflictions and the End of the World · “Do not renegade as disbelievers after me by striking the neck of one another.”
Narrated Ibn `Umar:
حَدَّثَنَا حَجَّاجُ بْنُ مِنْهَالٍ ، حَدَّثَنَا شُعْبَةُ ، أَخْبَرَنِي وَاقِدٌ ، عَنْ أَبِيهِ ، عَنِ ابْنِ عُمَرَ ، أَنَّهُ سَمِعَ النَّبِيَّ صلى الله عليه وسلم يَقُولُ " لاَ تَرْجِعُوا بَعْدِي كُفَّارًا، يَضْرِبُ بَعْضُكُمْ رِقَابَ بَعْضٍ " .
I heard the Prophet (ﷺ) saying, "Do not revert to disbelief after me by striking (cutting) the necks of one another."