Sahih Muslim Book 020, Hadith Number 4477.
Chapter : The people are subservient to the Quraish and the Caliphate is the right of the Quraish.
It has been narrated on the authority of Jabir b. Samura who said: I joined the company of the Holy Prophet (may peace be upon him) with my father and I heard him say: This Caliphate will not end until there have been twelve Caliphs among them. The narrator said: Then he (the Holy Prophet) said something that I could not follow. I said to my father: What did he say? He said: He has said: All of them will be from the Quraish.