Musnad Ahmad 5:375

Abdullah narrated to us, Abu Khaythama Zuhayr ibn Harb narrated to us, Waki' narrated to us. And Ishaq ibn Isma'il narrated to us, Abu Mu'awiyah and Waki' narrated to us, from Hisham ibn 'Urwah, from his father, from Abdullah ibn Ja'far, from Ali ibn Abi Talib, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The best of its women is Khadijah, and the best of its women is Maryam."