Through his theological works, Imam explains as following:
In the same way as the victims of ‘ujb (who think highly of themselves), by advancing step by step in transgression and sinfulness, ultimately reach the stage of apostasy, in the same way those affected by ‘ujb in their devotional activities and worship also advance day by day from the lower stages of ‘ujb to its higher levels.
The snares and designs of Satan and the self are not haphazard, but according to a calculated plan. It is not possible that the Devil would induce a God-fearing person of a clean character to commit a sin like murder or fornication, nor would he provoke a person possessing an honest nature and a pure soul to commit theft or a highway robbery.
It is not the case that from the very first day he will ask you to consider your good deeds as a favor done to God or to include yourself in the category of the Divine saints, His favorite servants, and those nearest to Him.
In the beginning he starts at the bottom and in a low key.
He steals into your heart and persuades you to be extremely careful and dedicated regarding the recommended duties (mustahabbat), prayers, and acts of piety.
While you do this, he will turn your attention towards the sins of a certain sinner and will make you compare his deeds with your own. Then he will whisper into your ears that you have enough grounds, both on a rational as well as a religious basis, to consider yourself superior to that person, Imam further explained.
Indeed your deeds will be the source of your redemption and that by the grace of God you are pious and pure and free from all vices.
He achieves two things through these kind of insinuations: first, it inculcates a feeling of general distrusts regarding the creatures of God; second, it makes the person imbued with a feeling of self-satisfied conceit. Both of these qualities are destructive and the sources of various vices and evils.
At this juncture, you should tell your self and the Devil that it is possible that this person who is guilty of committing that sin may possess other good qualities unknown to you or might have performed certain good deeds for which God may bless him with His grace and mercy, and the light of his good deeds and good qualities may guide him and ultimately lead him to deliverance.
Perhaps God Almighty has afflicted him with this sin, so as to protect him from ‘ujb, which is worse than sin. It is said in a hadith of al-Kafi.
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