Jami` at-Tirmidhi 2193
جامع الترمذي#2193Sahihحَدَّثَنَا أَبُو حَفْصٍ، عَمْرُو بْنُ عَلِيٍّ حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، حَدَّثَنَا فُضَيْلُ بْنُ غَزْوَانَ، حَدَّثَنَا عِكْرِمَةُ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ تَرْجِعُوا بَعْدِي كُفَّارًا يَضْرِبُ بَعْضُكُمْ رِقَابَ بَعْضٍ " . قَالَ أَبُو عِيسَى وَفِي الْبَابِ عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ وَجَرِيرٍ وَابْنِ عُمَرَ وَكُرْزِ بْنِ عَلْقَمَةَ وَوَاثِلَةَ بْنِ الأَسْقَعِ وَالصُّنَابِحِيِّ . وَهَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
Ibn 'Abbas narrated that the Messenger of Allah(s.a.w) said:"Do not revert to disbelief after me, some of you striking the necks of others
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 33:36