Surah Al-Mutaffifin — Ayah 14 (83:14)
كـَلَّاۖ بَلۡۜ رَانَ عَلَىٰ قُلُوبِهِم مَّا كَانُواْ يَكۡسِبُونَ ١٤
English translation (Saheeh International)
No! Rather, the stain has covered their hearts of that which they were earning.1
- - i.e., their sins.
Brief commentary
The matter is not as these deniers thought. Instead, the sins they used to commit has dominated and covered their minds and they therefore have not seen the truth with their hearts.