(8) باب قَوْلِ النَّبِيِّ صلى الله عليه وسلم " لاَ تَرْجِعُوا بَعْدِي كُفَّارًا، يَضْرِبُ بَعْضُكُمْ رِقَابَ بَعْضٍ
Narrated Ibn `Umar:
I heard the Prophet (ﷺ) saying, "Do not revert to disbelief after me by striking (cutting) the necks of one another."
Reference: Sahih al-Bukhari 7077
In-book reference: Book 92, Hadith 28
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 9, Book 88, Hadith 198