He says “the heart is the authoritative force or in charge of the body, if it is good then all of the body is good, but if it is corrupted then all of the body is corrupted”, as is mentioned from the statement of the
prophet صلى الله عليه و سلم in the hadeeth of Nu’man Ibn Bashir. He says “the origin of the heart of a believer is that it is a heart which is alive, and that is because it has become influenced by revelation (Quraan, speech of Allah) and the light which the prophet صلى الله عليه و سلم came with”.
He continues by saying “as for the heart of a disbeliever, a polytheist and the apostate, then this a heart which is dead, there is no life in it, and that is because it has not been influenced or affected by revelation and the light which the prophet صلى الله عليه و سلم came with in order for it to come to life”. He says “therefore the hearts comes to life with revelation (Quraan, Allah’s Speech) just as the earth comes to life with rain, and whenever revelation is prevented from reaching the heart, it dies. This is the heart of a kaafir (disbeliever)”.
Notes by Abuabdilmaalik Abdulhaqq Ibn Islaam
taken from Shaykh Fawzaan’s class on Igaathatul Lahfaan.