Quran 18:57 — The Cave (Al-Kahf)

Who are more evil than those who are reminded of their Lord's proofs, then disregard them, without realizing what they are doing. Consequently, we place shields on their hearts to prevent them from understanding it (the Quran), and deafness in their ears. Thus, no matter what you do to guide them, they can never ever be guided.

[18:56] We only send the messengers as simply deliverers of good news, as well as warners. Those who disbelieve argue with falsehood to defeat the truth, and they take My proofs and warnings in vain.

[18:58] Yet, your Lord is the Forgiver, full of mercy. If He called them to account for their deeds, He would annihilate them right there and then. Instead, He gives them a respite until a specific, predetermined time; then they can never escape.