Musnad Ahmad 25:202

Ibn Numayr narrated to us, Hajjaj informed us, from al-Hakam, from Miqsam, from Ibn Abbas, who said: When the Prophet (peace and blessings of Allah be upon him) left Makkah, he went out with the daughter of Hamzah. Ali, Ja’far, and Zayd disputed over her before the Messenger of Allah (peace and blessings of Allah be upon him). Ali said: "She is the daughter of my paternal uncle, and I brought her out." Ja’far said: "She is the daughter of my paternal uncle, and her maternal aunt is with me." Zayd said: "She is the daughter of my brother." Zayd had been made a brother to Hamzah; the Messenger of Allah (peace and blessings of Allah be upon him) had established brotherhood between them. The Messenger of Allah (peace and blessings of Allah be upon him) said to Zayd: "You are my freedman (mawla) and her guardian (mawla)." He said to Ali: "You are my brother and my companion." And he said to Ja’far: "You resemble my physical appearance and my character, and she belongs to her maternal aunt."