Musnad Abu Ya'la al-Mawsili 177:1

Surayj ibn Yunus Abu al-Harith narrated to us, Abu Mu'awiyah narrated to us, Hisham ibn 'Urwah narrated to us, from his father, from Hajjaj ibn Hajjaj, from his father, who said: I said, "O Messenger of Allah, what removes from me the blame of suckling?" He said, "The freeing of a male slave or a female slave."