Divine seal upon hearts

وَمَنْ أَظْلَمُ مِمَّن ذُكِّرَ بِـَٔايَـٰتِ رَبِّهِۦ فَأَعْرَضَ عَنْهَا وَنَسِىَ مَا قَدَّمَتْ يَدَاهُ ۚ إِنَّا جَعَلْنَا عَلَىٰ قُلُوبِهِمْ أَكِنَّةً أَن يَفْقَهُوهُ وَفِىٓ ءَاذَانِهِمْ وَقْرًا ۖ وَإِن تَدْعُهُمْ إِلَى ٱلْهُدَىٰ فَلَن يَهْتَدُوٓا۟ إِذًا أَبَدًا

And who is more unjust than one who is reminded of the verses of his Lord but turns away from them and forgets what his hands have put forth? Indeed, We have placed over their hearts coverings, lest they understand it, and in their ears deafness. And if you invite them to guidance - they will never be guided, then - ever.

كَذَٰلِكَ يَطْبَعُ ٱللَّهُ عَلَىٰ قُلُوبِ ٱلَّذِينَ لَا يَعْلَمُونَ

Thus does Allāh seal the hearts of those who do not know.