﴿ كَلَّا ۖ بَلْ ۜ رَانَ عَلَىٰ قُلُوبِهِم مَّا كَانُوا۟ يَكْسِبُونَ ﴾

“Nay, but their hearts are corroded by all [the evil] that they were wont to do!”

Literally ‘A prison’. It means a certain place in which the record of the deeds of the wicked is preserved.