The Forgiver - 40:35
Those who argue against the signs and miracles of Allah without any proof are subject to great anger both in the sight of Allah and in the sight of the believers. That is how Allah seals the heart of every arrogant tyrant.
That their understanding may be completely removed, that they may never again find the right path:
The Women/4:155
"Allah sealed their understanding because of their breaking their word, because they disbelieved in the signs and proofs of Allah, because they killed the prophets unjustly, and because they said: "We are fixed-minded", yes, because of their disbelief. Therefore few of them believe."
The Kneeling/45:23
Have you paid attention to him who takes his desire as a god? Allah has deliberately led him astray, and has sealed his hearing and his brain and put a veil over his sight. Who can guide him to the truth except Allah? Do you not take admonition?
The Hypocrites/63:3
Because they disbelieved after they believed, so their hearts were sealed; they do not understand.
The Pilgrimage/22:46
Have they not traveled the earth with thinking minds and hearing ears? The real blindness is not the blindness of the eyes, but the blindness of the hearts in the breasts.
The Heights/7:100
Has it not become evident to those who inherited the earth in place of the previous generations that if We willed, We could punish them with their sins and seal their hearts so that they could not hear?