Musnad Ahmad 32:823

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, and Hajjaj narrated to us, he said: Shu'bah narrated to me, he said: I heard Qatadah narrating from Anas ibn Malik, who said: The Messenger of Allah, peace and blessings of Allah be upon him, gathered the Ansar and said: "Is there anyone among you who is not of you?" They said: "No, except for a son of our sister." The Messenger of Allah, peace and blessings of Allah be upon him, said: "The son of a people's sister is one of them." Hajjaj said: "Or from themselves." He then said: "Verily, the Quraish are recently removed from the Age of Ignorance and calamity, and I intend to console them and reconcile them. Are you not pleased that the people return with the world, while you return with the Messenger of Allah to your homes? If the people were to travel through a valley, and the Ansar were to travel through a mountain pass, I would travel through the mountain pass of the Ansar."