Imam Al-Baqir (a.s.) said:
إِنَّ لِلّهِ عُقُوباتٌ فِى الْقُلُوبِ وَ الأَبْدان: ضَنْكٌ فِى الْمَعيشَةِ وَ وَهْنٌ فِى الْعِبادَةِ وَ ما ضُرِبَ عَبْدٌ بِعُقُوبَة أَعْظَمُ مِنْ قَسْوَةِ الْقَلْبِ!
God chastises man (for sins and disobedience) through the spirit and the body: indigence in livelihood, indolence in worship, but God has not punished any servant with something worse than hardheartedness.1
Divine chastisements are indeed reflections of man’s actions as well as the consequences of his sins. Sometimes they appear as an unpleasant situation in material life and sometimes in spiritual matters such as the lack of enthusiasm for worship and invocation to God. But the worst punishment meted out is that of making a person hard-hearted. The heart becomes devoid of humanitarian feelings, philanthropy and sympathy, and leads to perpetration of cruelty and many other sins.