What is the remedy for hardness of heart, following whims and desires, and the heart being veiled?

The treatment for the hardness of the heart and its serious illness lies in four matters: The Noble Quran, for it is a healing for the chests, removing doubt, polytheism, and the ailments of suspicions and desires. Preserving the heart's strength and substance is achieved through faith, righteous deeds, and regular acts of obedience. Abstaining from harm is done by avoiding sins and transgressions. Expelling every harmful substance is accomplished through repentance and seeking forgiveness.