Musnad Abu Ya'la al-Mawsili 150:308

Ibrahim ibn al-Hajjaj al-Sami narrated to us, Wahib narrated to us, from Ayyub, from Abdullah ibn Abi Mulaykah, from Abdullah ibn al-Zubayr, from Aisha, that the Messenger of Allah (may Allah bless him and grant him peace) said: "One suckling does not make unlawful, nor do two sucklings."