Musnad Abu Ya'la al-Mawsili 3:262

Narrated to us Mujahid ibn Musa, narrated to us Abu Usamah, from Hisham, from his father, who said: I heard Abdullah ibn Ja'far saying: I heard Ali in Kufa saying: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "The best of its women is Maryam bint Imran; she is the best of its women in her day. And the best of its women is Khadijah bint Khuwaylid."