The Prophet ﷺ said, "Do not return to disbelief after me, striking the necks of one another."
أخبرنا أحمد بن عبد الله بن الحكم قال حدثنا محمد بن جعفر قال حدثنا شعبة عن واقد بن محمد بن زيد أنه سمع أباه
عن النبي ﷺ قال لا ترجعوا بعدي كفارا يضرب بعضكم رقاب بعض
Narrated by Muslim, in the Book of Faith, chapter explaining the meaning of the Prophet's ﷺ saying, "Do not return to disbelief after me, striking one another's necks," hadith no. 120/66, from the hadith of Muhammad bin Jafar Ghundar.And by Bukhari, in the Book of Blood Money, chapter "And whoever gives life to it," hadith nos. 6868, 7077, and 6166, from the hadith of Shubah with the same wording.It is also found in Kubra, hadith no. 3590.