Not a [single] city which We destroyed believed before them, so will (21:6)

Almuntakhab Fi Tafsir Alquran Alkarim

In response to their insolence and defiance-, Allah says: Miraculous signs were presented to generations before them whom We reduced to a useless form on account of their rejection and denial of divine truth, therefore, what chance is there that these infidels will recognize Allah and in Him they will believe

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

(21:6) The fact, however, is that no habitation, which We destroyed before them, believed (in spite of signs); now, will they, then, believe ? *8

Not a [single] city which We destroyed believed before them, so will meaning

*8) This contains a concise answer to the demand for a sign to the effect
(1) You ask for Signs like the ones which were shown by the former Messengers but you forget that those obdurate people did not believe in spite of the Signs shown to them.
(2) While demanding a Sign, you fail to realize that the people, who disbelieved even after seeing a Sign, were inevitably destroyed.
(3) It is indeed a favour of Allah that He is not showing the Sign as demanded by you. Therefore, the best course for you would be to believe without seeing a Sign. Otherwise, you will meet the same doom that the former communities met, when they did not believe even after seeing the Signs.
 

Not a [single] city which We destroyed believed before them, so will meaning in Urdu

حالاں کہ اِن سے پہلے کوئی بستی بھی، جسے ہم نے ہلاک کیا، ایمان نہ لائی، اب کیا یہ ایمان لائیں گے؟