Chapter 34: The Book on Government
It has been narrated on the authority of Jabir b. Samura who said: I heard the Messenger of Allah (ﷺ) say: Islam will continue to be triumphant until there have been twelve Caliphs. Then the Prophet (ﷺ) said something which I could not understand. I asked my father: What did he say? He said: He has said that all of them (twelve Caliphs) will be from the Quraish.
Sahih Muslim 1821d