﴿ أَفَلَا يَتَدَبَّرُونَ ٱلْقُرْءَانَ أَمْ عَلَىٰ قُلُوبٍ أَقْفَالُهَآ ﴾

“Will they not, then, ponder over this Qur’an? - or are there locks upon their hearts?”

أَمْ عَلَىٰ قُلُوبٍ أَقْفَالُهَا (or do they have locks on their hearts? - 47:24) The meaning of this phrase is synonymous with similar phrases in other verses of the Qur'an where words like khatm or tab' "[ Allah ] has set a seal [ on their hearts ] have been used to describe how the disbelievers refuse to employ their hearts for the comprehension of truth, as a natural consequence their capacities to distinguish right from wrong have become atrophied. Carelessly, committing sins all the time is the main cause of this. Allah forbid!