Musnad Ahmad 1153:850

Sulayman ibn Dawud narrated to us, he said: Abd al-Rahman informed us, from Hisham ibn Urwah, from his father, who said: Aisha said: "The Messenger of Allah, may Allah bless him and grant him peace, married me while I was a girl of six years in Mecca, after the death of Khadija. And he consummated the marriage with me while I was a girl of nine years in Medina."