Sayyiduna Jabir bin Samurah (may Allah be pleased with him) said: I was with my father in the presence of the Prophet (peace and blessings be upon him), and I heard him (peace and blessings be upon him) say: "After me there will be twelve amirs." Then he (peace and blessings be upon him) lowered his voice. I asked my father: "I heard the Messenger of Allah (peace and blessings be upon him) say: 'After me there will be twelve amirs', so what was it that he (peace and blessings be upon him) said quietly?" He told me: "He (peace and blessings be upon him) said: 'All of them will be from Quraysh.'"
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2049