The late founder of the Islamic Republic in his famous book "Combat with the self" explains the matter as following:
This devotion is truly an introduction to admonish and prepare man to accept the responsibilities of the blessed month of Ramadan, and it is possible that it is also to remind the aware person of the motive for fasting and its valuable fruits.
The immaculate Imams, peace be with them, have explained many things by the tongue of supplication. The tongue of supplication is very different from the other tongues by which those greats explained precepts.
They have explained most spiritual, metaphysical, and precisely divine matters, and that which is related to knowledge of Allah by the tongue of supplication. But we recite supplications to the end and unfortunately pay no attention to their meanings, and we fail to understand what they really want to say.
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Imam stressed tasks should be done for pure divine sake
In this munajat we read: “O my God! Grant that I may be perfectly cut off from all else but You, and enlighten the vision of our hearts by the radiance of vision toward You, until the visions of the heart tear through the curtains of light and attach to the Source of Greatness and our souls come to belong to Your Exalted Sanctity.”
It is possible that the meaning of the sentence, “O my God! Grant that I may be perfectly cut off from all else but You,” is that prior to the blessed month of Ramadan, divinely aware people should get ready and prepare themselves for cutting themselves off and avoiding worldly pleasures (and this avoidance is that very being cut off perfectly from all else but Allah).
Being perfectly cut off from all else is not something easily obtained, Imam further explained.
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Imam Khomeini advised believers to fill their hearts with light of divine knowledge