ك-ف-ر

إِنَّ ٱلَّذِينَ كَفَرُوا۟ سَوَآءٌ عَلَيْهِمْ ءَأَنذَرْتَهُمْ أَمْ لَمْ تُنذِرْهُمْ لَا يُؤْمِنُونَ

As for the Disbelievers, Whether thou warn them or thou warn them not it is all one for them; they believe not.

أَوْ كَصَيِّبٍ مِّنَ ٱلسَّمَآءِ فِيهِ ظُلُمَـٰتٌ وَرَعْدٌ وَبَرْقٌ يَجْعَلُونَ أَصَـٰبِعَهُمْ فِىٓ ءَاذَانِهِم مِّنَ ٱلصَّوَٰعِقِ حَذَرَ ٱلْمَوْتِ ۚ وَٱللَّهُ مُحِيطٌۢ بِٱلْكَـٰفِرِينَ

Or like a rainstorm from the sky, wherein is darkness, thunder and the flash of lightning. They thrust their fingers in their ears by reason of the thunder-claps, for fear of death, Allah encompasseth the disbelievers (in His guidance, His omniscience and His omnipotence).

وَقَالُوا۟ قُلُوبُنَا غُلْفٌۢ ۚ بَل لَّعَنَهُمُ ٱللَّهُ بِكُفْرِهِمْ فَقَلِيلًا مَّا يُؤْمِنُونَ

And they say: Our hearts are hardened. Nay, but Allah hath cursed them for their unbelief. Little is that which they believe.