Musnad Ahmad 5:208

Yahya ibn Adam narrated to us, Isra'il narrated to us, from Abu Ishaq, from Hani ibn Hani and Hubayrah ibn Yarim, from Ali, who said: When we left Makkah, the daughter of Hamzah followed us, calling out: "O uncle! O uncle!" He said: So I took her by her hand and handed her to Fatimah, and I said: "Take your cousin." He said: When we arrived in Al-Madinah, Ja'far, Zayd ibn Harithah, and I disputed over her. Ja'far said: "She is the daughter of my paternal uncle, and her maternal aunt is with me"—meaning Asma bint Umays. Zayd said: "She is the daughter of my brother." And I said: "I took her, and she is the daughter of my paternal uncle." The Messenger of Allah (peace and blessings of Allah be upon him) said: "As for you, O Ja'far, you resemble my physical appearance and my character. As for you, O Ali, you are from me and I am from you. And as for you, O Zayd, you are our brother and our freedman. The girl shall be with her maternal aunt, for the maternal aunt is like a mother." I said: "O Messenger of Allah, will you not marry her?" He said: "She is the daughter of my brother through breastfeeding."