One of the disadvantages of a hardened heart is the individual becomes bold in committing sins. The horrors of the grave, fear of the Day of Judgement, accountability in the Hereafter, and the punishment of Hell do not concern him at all. After disregarding good advice, such a person becomes bold and outspoken, which sometimes leads to disrespect against Allah Almighty and His Messenger صَلَّى اللهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم, resulting in him losing his faith.

The renowned commentator of the Quran, Mufti Aḥmad Yār Khan NaꜤīmī رَحْمَةُ الـلّٰـهِ عَـلَيْه said:

With regards to the person who is bold enough to utter all sorts of good and bad without hesitation, know that his heart is hard and it has no shame. Hard-heartedness is a tree which plants its roots in the heart and its branches are in Hell. The outcome of such a careless individual is that he becomes a disbeliever by disrespecting Allah Almighty and His Messenger صَلَّى اللهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم.^[1]

صَلُّوۡا عَلَى الۡحَبِيۡب                                     صَلَّى اللّٰهُ عَلٰى مُحَمَّد

Second harm

The second harm of this ailment is it deprives one from the worship of Allah Almighty, the recitation of the noble Quran, and from performing good deeds. Allah Almighty states:

وَ مَا خَلَقْتُ الْجِنَّ وَ الْاِنْسَ  اِلَّا لِیَعْبُدُوْنِ (۵۶)

And I did not create jinn and mankind but to worship me. ^[2]

Allah Almighty also said: