Musnad Ahmad 907:16

Ibn Numayr narrated to us, Mujalid narrated to us, from ‘Amir, from Jabir ibn Samurah al-Suwa’i, who said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying during the Farewell Pilgrimage: "This religion will continue to be manifest over those who oppose it; it will not be harmed by those who differ with it, nor by those who separate from it, until twelve amirs pass from my Ummah, all of them..." Then the words of the Messenger of Allah, peace and blessings of Allah be upon him, became unclear to me. He said: My father was closer to the mount of the Messenger of Allah, peace and blessings of Allah be upon him, than I was. So I said: "O my father, what was it that was unclear from the words of the Messenger of Allah, peace and blessings of Allah be upon him?" He said: "He said: 'All of them are from Quraysh.'"