“The heart becomes well when it acquires knowledge of its Lord and Creator and in His Names, Attributes, Actions and Commandments.”
“The heart in addition becomes well when it prefers acquiring Allah's Pleasure and prefers what He likes, all the while avoiding His prohibitions and what might lead to His displeasure.”
“There is no life, health, or wellbeing for the heart except by this method, which only the Messengers can provide. It is wrong to think that one can ever attain the hearts wellbeing through any other way than through the guidance of the Messengers of Allah.”
“These errors result from confusing the heart's true wellbeing with satisfying and strengthening its lower animal lusts and desires. By this way, the heart will be far from acquiring its true wellbeing, strength and even its very existence will be in danger.”
Ibn Qayyim al-Jawziyya in “Prophetic Medicine”