Diseases of the Hearts & their Cures
It is very important to spend time and energy in treating the heart, and hastening to correct and cleanse it from disease and all sins. The heart occupies a great and lofty place in Islam, for it is the place to which the Lord looks and the place for tawheed, faith and honesty. The heart has been singled out for because it is the chief of the body, and through the purification of the chief the subjects become purified, and with his corruption they become corrupted.
by Shaykuhl- Islam Ibn Taymiyyah