Why should we obey Allah ta’ala? Why should we abstain from sin and wrongdoing? For the one who has a living heart, this is a question that need not even be asked. It is only those who hearts are hardened – or worse, deceased – who would contemplate it. – A paralysed person might place his hand on a burning plate and have no problem in doing so, since he does not feel any pain. But a fully healthy person will immediately snatch his hand away, once he feels the searing heat. The one whose heart is hardened is like the paralysed person – he sins… and feels nothing. But the one whose heart is alive with imaan and taqwa, feels the pain and ill-effects caused to his heart by the sins he commits. – Mustafa has told us that with every sin we do, with every temptation we succumb to, a black spot is marked on our hearts. (1) A sinner continues in this way, perpetrating evil and haram, until his heart becomes completely blackened and hardened. And that is the raan upon the hearts, of which our Lord speaks:
كَلَّا بَلْ ۜ رَانَ عَلَىٰ قُلُوبِهِم مَّا كَانُوا يَكْسِبُونَ
Nay! But on their hearts is the raan which they used to earn.
(1): Mentioned in a hadith recorded in Sahih Muslim.