It is narrated from Sayyiduna Amr bin Awf bin Milhah al-Muzani (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) was sitting with them. He went into his house and said: "Come in to me, and let no one come in to me except a Qurayshi." I slipped in quietly, and the Messenger of Allah (peace and blessings be upon him) said: "O people of Quraysh, is there anyone among you who is not one of you?" They said: O Messenger of Allah, may our fathers and mothers be ransomed for you, we inform you that with us are a sister's son and a freed slave. The Messenger of Allah (peace and blessings be upon him) said: "The ally of a people is one of them, the freed slave of a people is one of them, and the sister's son of a people is one of them. O people of Quraysh, you are the ones who will hold authority over this matter (the caliphate) after me, so do not die except as believers. Hold fast, all of you together, to the rope of Allah and do not be divided, and do not be like those who became divided and differed after clear proofs had come to them. They were commanded only to worship Allah, sincere to Him in religion, upright, and to establish the prayer and give zakah, and that is the upright religion. O people of Quraysh, keep my regard concerning my Companions, their children and their children's children. May Allah have mercy on the Ansar and the children of the Ansar."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14074