"As for the sicknesses of the hearts, its remedy is the prophetic medicine. The doctors cannot treat this sickness. It's possible that they (the doctors) themselves are sick, however the remedy is in the prophetic medicine. Busy yourself with the remembrance of Allaah, the legislated words of remembrance. It is upon you to choose books of al-Adhkaar (the words of the remembrance of Allaah), al-Adhkaar by an-Nawawi, al-Waabil as-Sayyib, al-Kalamut Tayyib and Saheeh al-Kalam at-Tayyib. Also (one should have) other than that from the Adhkaar, the books that have gathered the related Adhkaar, clarified the virtue of al-Adhkaar and the status of al-Adhkaar in order that you don't forget Allaah. If you were to forget Allaah you will be destroyed and you will have fallen into all types of pain. When the sickness has been diagnosed the remedy of it becomes easy. Therefore when we come to know of these different types of sickness, it is upon us to work hard in the usage of the remedy. With Allaah is all the success"
Taken from the Shaykh's explanation of Asbaabu Sharhis Sadr p.g. 62-63