question #1 Sahih al-Bukhari 121, Book 3, Hadith 63 : What warning did the Prophet Muhammad (ﷺ) give regarding the behavior of Muslims towards each other after his passing?

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).