Imam Khomeini has undertaken very useful discussions with this regard in his famous book of "the combat with the self" as following:
He whose Guardian [wali] is God, the Blessed and Exalted, and who is taken by Him out from the darkness never commits another sin, never backbites, never slanders others, and he is never vengeful or envious of his brothers in faith. His own heart is filled with a feeling of luminosity and he no longer holds the world or what it contains in high esteem.
As Imam ‘Ali (as) said, “If all the world and what it contains were offered to me to cruelly and unjustly take the skin of a grain of barley from the mouth of an ant, I would never accept it.”
But some of you trample over everything, and you backbite the great [scholars] of Islam. If others speak ill of the grocers and perfume sellers on the street and backbite them, for your part some of you relate unfair things, insult and are impudent toward the scholars of Islam, because you are not firmly grounded in faith and you do not believe in [divine] retribution for your own deeds.
Actually, man would not recklessly run wild if he considered it all likely, he need not have certainty, that which is reported in the Noble Qur’an is right, the promises and the threats, and that he should amend his ways and deeds.
If you consider it all likely that ferocious beasts are to be found along the path which might harm you, or that there are armed bandits who might hold you up, you would refrain from taking that path, and you would try to ascertain the correctness or incorrectness of these reports, Imam further explained.
Is it possible for someone to consider it possible that hell exists and that one may remain forever in its fire while at the same time doing wrong? Can it be said that one who considers God Almighty to be present and watching and Who sees himself to be in the presence of the Lord, and who considers it possible that there should be retribution for his words and deeds, a reckoning and chastisement, and that in this world every word he speaks, every step he takes, every deed he does, is recorded by angels of Allah called ‘Raqib and ‘Atid,’ and they carefully record all his words and deeds, and in such a state, could he fearless of his own doing?
If man is certain and has faith that all the outward and inward worlds are in the presence of the Lord, and that God, the Exalted, is present everywhere and sees everything, in the presence of God and God’s blessings there would be no possibility for committing sins.
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