And if We had made him an angel, We would have made (6:9)

Almuntakhab Fi Tafsir Alquran Alkarim

And if We had sent an angel as a Messenger or to companion Our human Messenger, We would have disguised him as a man, and there one disorder would be aggravated by another; they would not believe in him either, and a fallacious mode of reasoning would be created more than ever; they would not know whether to use the premise to prove the conclusion or to use the conclusion to prove the premise - a vicious circle

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(6:9) Had We appointed an angel, We would have sent him down in the form of a man - and thus We would have caused them the same doubt which they now entertain. *7

And if We had made him an angel, We would have made meaning

*7). This is the second point in response to the unbelievers' objection. One possible form in which the angel could have appeared is in its true, non-terrestrial form. It has already been pointed out that the time for this has not arrived. Alternatively, angels could have come down in human form. But this would have left the unbelievers facing the same difficulty as they faced with regard to whether the Prophet Muhammad (peace be on him) had been designated by God or not.
 

And if We had made him an angel, We would have made meaning in Urdu

اور اگر ہم فرشتے کو اتارتے تب بھی اسے انسانی شکل ہی میں اتارتے اور اس طرح انہیں اُسی شبہ میں مبتلا کر دیتے جس میں اب یہ مبتلا ہیں