Usamah bin Zayd (may Allah be pleased with him) said: I passed by the mosque and saw Ali and al-Abbas (may Allah be pleased with them both) sitting. They said: O Usamah, seek permission for us from the Messenger of Allah (peace and blessings be upon him). I said: O Messenger of Allah, Ali and al-Abbas are at the door; they wish to come in to you. He (peace and blessings be upon him) said: "Do you know what has brought them?" I said: No, by Allah, O Messenger of Allah, I do not know what has brought them. He (peace and blessings be upon him) said: "But I know what has brought them; give them permission." So they both came in, and Ali said: O Messenger of Allah, we have come to ask you: which of your family is most beloved to you? He (peace and blessings be upon him) said: "Fatimah bint Muhammad." Ali said: By Allah, O Messenger of Allah, we are not asking you about your family. He (peace and blessings be upon him) said: "Then the most beloved to me of my (other) family is the one upon whom Allah bestowed favour and upon whom I bestowed favour: Usamah." He asked: Then who, O Messenger of Allah? He (peace and blessings be upon him) said: "Then you." Al-Abbas said: Have you put your uncle last of them? He (peace and blessings be upon him) said: "Ali preceded you in emigration (Hijrah)."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 366