Sayyiduna Abdullah bin Ja'far (may Allah be pleased with them both) said: If only you had seen me and Qutham and Ubaydullah (may Allah be pleased with them both), the two sons of Sayyiduna al-Abbas (may Allah be pleased with him), as we were playing, when the Messenger of Allah (peace and blessings be upon him) passed by us on his mount and said: "Lift this one up to me," and he seated me in front of him. Then he said about Qutham: "Bring this one to me as well," and he seated him behind him. He was not embarrassed before his uncle al-Abbas (may Allah be pleased with him) that he carried Qutham and left Ubaydullah. Then he passed his hand over my head three times, and each time he said: 'Allahumma ikhluf Ja'faran fi waladihi' (O Allah, be Ja'far's successor among his children [make his children as he was]). I said to Abdullah bin Ja'far (may Allah be pleased with them both): What became of Qutham? He said: He was martyred. So I said to Abdullah: Allah and His Messenger knew best what was good for him. He said: Yes, indeed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 7093