كَذَٰلِكَ سَلَكْنَٰهُ فِى قُلُوبِ ٱلْمُجْرِمِينَ
Commentary:
The pronoun 'it' in the expression "thus have We caused it to enter" referring to the evil practice of the disbelievers of rejecting truth the verse purports to say that this bad habit of disbelievers has its roots in their own hearts and is born of their indulgence in sin and vice and does not come from outside. The verse, in fact, states a general truth that when a man indulges in sin his consciousness of it becomes blunted and in course of time he even comes to develop a liking for it. It is in this way that sin corrodes and vitiates "the hearts of the sinful."
Or the pronoun 'it' may refer to the Quran. In this sense the verse would mean that the truth of the Quran is made to enter into the hearts of disbelievers by means of the convincing proofs and arguments given in support of it. They become conscious of its truth but still they reject it.
This bad habit of disbelievers has its roots in their own hearts and is born of their indulgence in sin and vice and does not come from outside. The verse, in fact, states a general truth that when a man indulges in sin, his consciousness of it becomes blunted and in the course of time he even comes to develop a liking for it. It is in this way that sin corrodes and vitiates 'the hearts of the sinful.'