﴿ لَوْ يَعْلَمُ ٱلَّذِينَ كَفَرُوا۟ حِينَ لَا يَكُفُّونَ عَن وُجُوهِهِمُ ٱلنَّارَ وَلَا عَن ظُهُورِهِمْ وَلَا هُمْ يُنصَرُونَ ﴾

“If they but knew - they who are bent on deny­ing the truth - [that there will come] a time when they will not be able to ward off the fire from their faces, nor from their backs, and will not find any succour!”

God exalted be He says If those who disbelieved only knew of the time when they shall not be able to ward off repel the Fire from their faces nor from their backs nor shall they be helped nor shall they be protected from it at the Resurrection the response to the conditional particle law ‘if only’ is something along the lines of ‘they would not have said that’.