Translation:

8. They say: "Why is not an angel sent down to him?" If We did send down an angel the matter would be settled at once and no respite would be granted them.

Notes (Tafseer)

841. 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.