question #1 Sahih Muslim 66b, Book 1, Hadith 131 : What warning did the Prophet Muhammad (peace be upon him) give regarding the behavior of Muslims after his departure?

It is narrated on the authority of Abdullah b. Umar that the Apostle (may peace and blessings be upon him) observed on the occasion of the Farewell Pilgrimage Woe unto you distress unto you! Don’t turn back as unbelievers after me by striking the necks of one another.