Musnad Abu Ya'la al-Mawsili 150:117

Bishr ibn al-Walid narrated to us, Sharik narrated to us, from Hisham ibn Urwah, from his father, from Aisha: That when Sawdah grew old, she gifted her day to Aisha. She said: And the Messenger of Allah, may Allah bless him and grant him peace, used to divide for me my day and her day. And she was the first woman he married to me.