Musnad Ahmad 1153:233

Yahya narrated to us, from Malik, who said: Abdullah ibn Dinar narrated to me, from Sulayman ibn Yasar, from Urwah, from Aisha, from the Prophet, peace and blessings of Allah be upon him: "What is forbidden by nursing is what is forbidden by birth." And from Abdullah ibn Abi Bakr, from Amrah, from Aisha, from the Prophet, peace and blessings of Allah be upon him, the like of it.