It is narrated from the Prophet of Islam who said: When the heart is clean and pure, all the body is clean and pure; and when the heart is impure, all the body will get contaminated. According to Imam Baqir (AS), there are three types of hearts.
- The ill-fated heart of disbeliever; which no good can be found in it.
- The inconsistent heart where both good and bad move in and out of it, and whichever is stronger, will dominate.
- The generous heart of the believer; where there is a light in it from Divine Lights which illuminates continuously, and even on the Day of Judgment that light will not go out .
 Montahal Amaal, Vol. 2, Page 520-521.