وَلَوْ أَنَّآ أَهْلَكْنَـٰهُم بِعَذَابٍ مِّن قَبْلِهِۦ لَقَالُوا۟ رَبَّنَا لَوْلَآ أَرْسَلْتَ إِلَيْنَا رَسُولًا فَنَتَّبِعَ ءَايَـٰتِكَ مِن قَبْلِ أَن نَّذِلَّ وَنَخْزَىٰ Qur’an Ta-Ha (20:134)Walaw ann a ahlakn a hum biAAa tha bin min qablihi laq a loo rabban a lawl a arsalta ilayn a rasoolan fanattabiAAa a y a tika min qabli an na th illa wanakhz a
Cf. 6:131 , 15:4 or {26:208-209}, where it is stressed that God never punishes man for any wrong committed in ignorance of what constitutes right and wrong in the moral sense - i.e., before making it possible for him to avail himself of divine guidance.
If the Sign mentioned in the last note did not convince them, it would mean that they were not true to their own faith. They were not straight with themselves. In justice they should have been punished for their falsehood. But they were given further respite. Or they would again have argued in a circle, and said: "If only Allah had sent us a living messenger we should have believed!" The living messenger they flout because they want a Sign. The Sign they wish to ignore, because they want a living messenger!