Al-Isra' - 17:46

وَجَعَلْنَا عَلَى قُلُوبِهِمْ أَكِنَّةً أَن يَفْقَهُوهُ وَفِي آذَانِهِمْ وَقْرًا وَإِذَا ذَكَرْتَ رَبَّكَ فِي الْقُرْآنِ وَحْدَهُ وَلَّوْاْ عَلَى أَدْبَارِهِمْ نُفُورًا
[17:46]
And We have placed coverings on their hearts and a heaviness in their ears lest they understand it, and when you mention your Lord alone in the Quran they turn their backs in aversion.
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).
And We place upon their hearts veils lest they should understand it, and in their ears a deafness; and when thou makest mention of thy Lord alone in the Qur'an, they turn their backs in aversion.