Narrated Ibn 'Umar:
that the Messenger of Allah (ﷺ) made bonds of brotherhood among his Companions. So 'Ali came crying saying: "O Messenger of Allah! You have made a bond of brotherhood among your Companions, but you have not made a bond of brotherhood with me and anyone." So the Messenger of Allah (ﷺ) said to him: "I am your brother, in this life and the next." (ES)
English reference (ES): Vol. 1, Book 46, Hadith 3720 (ES)
Arabic reference (ES): Book 49, Hadith 4086 (ES)