Sahih al-Bukhari 3455
صحيح البخاري#3455SahihNarrated Abu Huraira:The Prophet (ﷺ) said, "The Israelis used to be ruled and guided by prophets: Whenever a prophet died, another would take over his place. There will be no prophet after me, but there will be Caliphs who will increase in number." The people asked, "O Allah's Messenger (ﷺ)! What do you order us (to do)?" He said, "Obey the one who will be given the pledge of allegiance first. Fulfil their (i.e. the Caliphs) rights, for Allah will ask them about (any shortcoming) in ruling those Allah has put under their guardianship
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: 60:122