Al-Isra 17:46

وَجَعَلْنَا عَلَىٰ قُلُوبِهِمْ أَكِنَّةً أَن يَفْقَهُوهُ وَفِىٓ ءَاذَانِهِمْ وَقْرًۭا ۚ وَإِذَا ذَكَرْتَ رَبَّكَ فِى ٱلْقُرْءَانِ وَحْدَهُۥ وَلَّوْا۟ عَلَىٰٓ أَدْبَٰرِهِمْ نُفُورًۭا

And We put coverings over their hearts (and minds) lest they should understand the Qur'an, and deafness into their ears: when thou dost commemorate thy Lord and Him alone in the Qur'an, they turn on their backs, fleeing (from the Truth).