Musnad Abu Ya'la al-Mawsili 150:313

'Amr ibn Muhammad narrated to us, Ya'qub ibn Ibrahim ibn Sa'd narrated to us, my father narrated to us, from Muhammad ibn Ishaq, Muhammad ibn Ja'far ibn al-Zubayr narrated to me, from 'Urwah ibn al-Zubayr, from 'A'ishah, she said: "When I would part the hair of the Messenger of Allah (may Allah bless him and grant him peace) on his head, I would part it from the crown of his head, and I would let his forelock fall between his eyes. And Allah knows best whether that was because of the saying of the Messenger of Allah, 'We do not tuck up hair nor clothing,' or if it was a mark by which he was distinguished. And Muhammad ibn Ja'far ibn al-Zubayr—and he was a Muslim jurist—said to me: 'It is nothing but a mark from the marks of the Prophets, which the Christians have held onto, to the exclusion of other people.'"