21:39
لَوْ يَعْلَمُ ٱلَّذِينَ كَفَرُوا۟ حِينَ لَا يَكُفُّونَ عَن وُجُوهِهِمُ ٱلنَّارَ وَلَا عَن ظُهُورِهِمْ وَلَا هُمْ يُنصَرُونَ
If those who disbelieved but knew the time when they will not avert the Fire from their faces or from their backs and they will not be aided...
Translation · Saheeh International
Tafsir
Ibn Kathīr (abridged)
The Idolators seek to hasten on the Punishment
Allah also tells us how the idolators seek to hasten punishment upon themselves, out of denial, rejection, disbelief, stubbornness and a belief that it will never happen. He says:
وَيَقُولُونَ مَتَى هَـذَا الْوَعْدُ إِن كُنتُمْ صَـدِقِينَ
(And they say: "When will this promise (come to pass), if you are truthful".) And Allah says:
لَوْ يَعْلَمُ الَّذِينَ كَفَرُواْ حِينَ لاَ يَكُفُّونَ عَن وُجُوهِهِمُ النَّارَ وَلاَ عَن ظُهُورِهِمْ
(If only those who disbelieved knew (the time) when they will not be able to ward off the Fire from their faces, nor from their backs,) meaning, if only they knew for certain that it will inevitably come to pass, they would not seek to hasten it. If only they knew how the torment will overwhelm them from above them and from beneath their feet.