They say, ‘Why has not an angel been sent down to him?’ Were We to send down an angel, the matter would surely be decided, and then they would not be granted any respite.
— Ali Quli Qarai
Surah Al-‘An’am, Verse 8
وَقَالُواْ لَوْلا أُنزِلَ عَلَيْهِ مَلَكٌ وَلَوْ أَنزَلْنَا مَلَكًا لَّقُضِيَ الأمْرُ ثُمَّ لاَ يُنظَرُونَ
8. "And they said: ' Why has not an angel been sent down to him? And if We had sent down an angel, the matter would have certainly been determined, and then they would not be granted any respite."
The disbelievers protested why there were not sent down an angel to the Prophet (S) so openly that they could see him with their own eyes and, consequently, they might attest his prophet hood.
Then, in order to show that their disobedience has reached to its climax, the verse implies that had Allah sent down an angel as they wished, they would not have believed. So, the divine wisdom and common good required that Allah should not respite them any more, and would immediately involve them in a punishment to destroy them. The verse itself says: