The Messenger of Allah (ﷺ) established an alliance (of brotherhood) between the Emigrants and the Helpers in our house. He was asked: Did not the Messenger of Allah (ﷺ) say: There is no alliance in Islam ? He replied: The Messenger of Allah (ﷺ) established an alliance between the Emigrants and the Helpers in our house. This he said twice or thrice.
Sunan Abi Dawud Book 19, Hadith 42