Sahih al-Bukhari 4024
صحيح البخاري#4024SahihNarrated Said bin Al-Musaiyab: When the first civil strife (in Islam) took place because of the murder of 'Uthman, it left none of the Badr warriors alive. When the second civil strife, that is the battle of Al-Harra, took place, it left none of the Hudaibiya treaty companions alive. Then the third civil strife took place and it did not subside till it had exhausted all the strength of the people
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 64:73