17:46

“And We have put coverings over their hearts lest they should understand it (the Qur’an), and in their ears deafness. And when you make mention of your Lord Alone [La ilaha illallah (none has the right to be worshipped but Allah) Islamic Monotheism in the Qur’an, they turn on their backs, fleeing in extreme dislike.”

83:14

“Nay! But on their hearts is the Ran (covering of sins and evil deeds) which they used to earn.”

57:16

“Has not the time come for the hearts of those who believe (in the Oneness of Allah – Islamic Monotheism) to be affected by Allah’s Reminder (this Qur’an), and that which has been revealed of the truth, lest they become as those who received the Scripture [the Taurat (Torah) and the Injeel (Gospel)] before (i.e. Jews and Christians) and the term was prolonged for them and so their hearts were hardened? And many of them were Fasiqun (the rebellious, the disobedient to Allah).”