Surah 6. Al-An'am, Ayah 8

I.e., Judgment Day would have come - for it is only then that the forces described as angels will manifest themselves to man in their true form and become comprehensible to him. (Cf. a similar passage in 2:210 .)

 i.e., they would have been destroyed immediately upon denying the angel.

Cf. ii. 210. An angel is a heavenly being, a manifestation of God's glory, invisible to men who live gross material lives. Such men are given plenty of respite in which to turn in repentance to God and make theselves worthly of His light. But if their prayer to see an angel were grated, it would do them no good, for thy would be destroyed as darkness is destroyed by light.