Disease of the heart

• A disease of the heart, other than physical disease, can doubt. The proof for this is in Surah Baqarah (Ayah 10), for here the disease refers to doubt.
• A disease of the heart is a pain in the heart that occurs, such anger, the proof for this is in Surah At-Tawbah, Ayah 14-5: '...and heal the breasts of a believing people, (14) And remove the anger of their (believers') heart...'
• Healing can be the removal of the suffering such as people seeking retaliation for a murdered relative therefore they are seeking healing. Likewise, doubt and ignorance can cause pain to the heart: 'Prophet (SAW) said,"....could they not have asked if they did not know? Indeed the cure for ignorance to ask..." (Sunan Abu Dawud, Hadeeth number 336. The Hadeeth has a da' eef isnaad but is supported by the Hadeeth narrated by Ibn Abbaas in Sunan Ibn Majah, hadeeth number 126, which raises this hadeeth to being hasan. But the last part of the hadeeth beginning from "sprinkle" is still da'eef)
• So knowledge can be the healing of the heart by removing the ignorance or doubt. Quran is a cure for the heart, for the one who has doubt or desire, it contains clear proofs; so the reading of the Quran constantly is recommended.