If a person has hardness in his heart, what are some things which soften the hardening of a heart?
Shaykh Salih al-Fawzaan:
“There is nothing better, nor more necessary than the Noble Quran. It is the thing which soften the hearts. Allah said, “Those who believe (in the Oneness of Allah – Islamic Monotheism), and whose hearts find rest in the remembrance of Allah, Verily, in the remembrance of Allah do hearts find rest.” [13:28]. So that which softens the heart is the Quran. That which if Allah had sent it down “…on a mountain, you would surely have seen it humbling itself and rending asunder by the fear of Allah. Such are the parables which We put forward to mankind that they may reflect.” [59:21]
Likewise, sitting with the righteous ones, listening to the Quran, listening to advice and reminders, these are some of the things which soften the heart.