Musnad Ahmad 32:2042

'Affan narrated to us, Hafs ibn Ghiyath narrated to us, 'Asim al-Ahwal narrated to us, he said: I heard Anas, and a speaker said to him: "Has it reached you that the Messenger of Allah, peace and blessings of Allah be upon him, said: 'There is no confederacy (hilf) in Islam'?" He said: So he became angry, then he said: "Yes, yes, the Messenger of Allah, peace and blessings of Allah be upon him, established a confederacy between the Quraysh and the Ansar in his house."