The Book of Faith (Kitab Al-Iman)

Muslim :: Book 1 : Hadith 332

Zirr b. Hubaish narrated it on the authority of 'Abdullah (that the words of Allah):" Certainly he saw of the greatest signs of Allah" (al-Qur'an, liii. 18) imply that he saw Gabriel in his (original) form and he had six hundred wings.