Musnad Ahmad 26:421

Yahya narrated to us, Isra'il narrated to us, from Abu Ishaq, from 'Abd al-Rahman ibn Yazid, from 'Abdullah, regarding the saying of the Almighty, the Majestic: "The heart did not lie [about] what it saw" [An-Najm: 11]. He said: "The Messenger of Allah, peace and blessings of Allah be upon him, saw Gabriel in a garment of green silk (rafraf), having filled what is between the heaven and the earth."