Musnad Ahmad 287:2

Sufyan ibn 'Uyaynah narrated to us, from Isma'il—meaning Ibn Umayyah—from Ibn Abi Mulaykah, from 'Uqbah ibn al-Harith: I married the daughter of Abu Ihab. Then a black woman came—meaning [a nursemaid]—and she mentioned that she had suckled both of you. So I came to the Prophet, peace and blessings of Allah be upon him, and I stood before him and spoke to him, but he turned away from me. I stood to his right, and he turned away from me. I said: "O Messenger of Allah, she is only a black woman." He said: "And how [can you keep her] when it has been said?"