The Book of Faith (Kitab Al-Iman)
Muslim :: Book 1 : Hadith 330
Al-Shaibini reported to us: I asked Zirr b. Hubaish about the words of Allah (the Mighty and Great):" So he was (at a distance) of two bows or nearer" (al-Qur'an, Iiii 8). He said: Ibn Mas'ud informed me that, verily, the Apostle of Allah (may peace be upon him) saw Gabriel and he had six hundred wings.