discusses achieving Divine love and how to obtain it so that it becomes a guide in improving the quality of the practice of Islamic teachings.
And among the contents it also discusses

Various kinds of hearts

Al Israa 36 (translation):

"And do not follow what you do not have knowledge about. Indeed, hearing, sight and heart, all of them will be called to account."

Charity forms 3 kinds of heart:

A healthy heart is a living heart, a valid heart. It is the heart that is safe (qalbun salim). Safe and clean from heart disease, namely lust and doubt. Syahwat linguistically means attraction, interest; favorite. Shubhat is vagueness, confusion of thought.

A dead heart is a heart that does not know its Rabb, does not submit itself to Allah Ta'ala, who made its soul as its priest.

A sick heart is a heart that is still alive, but diseased. In general, immorality is liver poison, the most common being the 4 below:

Excessive in speaking.
Too much looking.
Excessive consumption of food and drink.
Too much socializing.

One of the remedies is to simplify yourself with what is halal so that you don't desire what is doubtful, let alone what is haram.