Musnad Ahmad 1153:2378

Hassan ibn Musa narrated to us, he said: Hammad ibn Salamah narrated to us, from Hisham ibn Urwah, from his father, from Aisha, who said: "The Messenger of Allah, may Allah bless him and grant him peace, married me after the death of Khadijah, two or three years before his departure to Medina, and I was a girl of seven years. When we arrived in Medina, women came to me while I was playing on a swing, and I had my hair gathered in a bunch. They took me, prepared me, and adorned me. Then they brought me to the Messenger of Allah, may Allah bless him and grant him peace, and he consummated the marriage with me while I was a girl of nine years."