Musnad Ahmad 1153:1168

Rawh narrated to us, Abdullah ibn Umar narrated to us, from his brother, from al-Qasim ibn Muhammad, from Aisha: That a man came to the Prophet, peace and blessings of Allah be upon him, on a pack horse, wearing a turban with its end between his shoulders. She asked the Prophet, peace and blessings of Allah be upon him, about him. He said: "Did you see him? That was Gabriel, peace be upon him."