Imam through his theological works explains the matter as following:
There are various kinds and degrees of hasad according to the state and condition of the mahsud (the one envied), the hasud (the one who envies), and the nature of hasad itself.
According to the condition of the mahsud: Qualities like certain intellectual, spiritual, and moral merits, or good and pious deeds, or outward factors like wealth, honor, and prestige can cause envy. Also their antithetical qualities, when they are imagined to be merits, can also cause envy and jealousy.
According to the condition of the envious person: The feeling of envy in the heart of the person who harbors it is sometimes caused by enmity, sometimes by pride, and at other times by fear and the like-causes which will be discussed later on.
According to the condition of envy itself: As for envy itself, the classification performed on its basis is an essential one, not those performed on the previous bases.
There are several stages and grades of intensity and weakness according to their various causes and effects. God willing, we will deal with their harmful effects and the methods of curing them in several sections according to our capabilities, and hope to receive His assistance in this regard.
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