Al-An'am 6:8

Waqaloo lawla onzila AAalayhimalakun walaw anzalna malakan laqudiya al-amruthumma la yuntharoon

And they say, "Why was there not sent down to him an angel?" But if We had sent down an angel, the matter would have been decided; then they would not be reprieved.

They say, “Why is it that an angel has not been sent down to him?” Had We sent down an angel, the whole matter would have been closed, and thereafter no further time would have been allowed to them.