Musnad Abu Ya'la al-Mawsili 117:116

Al-Fadl ibn al-Sabah Abu al-Abbas narrated to us, Abu Ubaydah al-Haddad narrated to us, from Muhtasib, from Thabit al-Bunani, from Anas ibn Malik, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "When will I meet my brothers?" They said: "O Messenger of Allah, are we not your brothers?" He said: "Rather, you are my companions. And my brothers are those who believed in me and did not see me."