Sahih Muslim Book 020, Hadith Number 4482.
Chapter : The people are subservient to the Quraish and the Caliphate is the right of the Quraish.
It has been reported on the authority of Jabir b. Samura who said: I went with my father to the Messenger of Allah (may peace be upon him) and I heard him say: This religion would continue to remain powerful and dominant until there have been twelve Caliphs. Then he added something which I couldn't catch on account of the noise of the people. I asked my father: What did he say? My father said: He has said that all of them will be from the Quraish.