The most frequently asked question about the story of Adam & his Garden is whether he made a mistake or committed a sin in partaking from the tree which he was forbidden to approach. According to al-Mizān, the story of Adam may have been used by God to represent the rise, fall and rise again of the whole mankind. Adam was the first representative of humanity, and his life was a symbol of the life span of human beings in this world. Therefore most people seem to have missed this Qur'anic reality.
The story of Adam and his placement in the Garden has been given in three places in the Qur'an: Chapter 2 (verses 35-39), Chapter 7 (verses 19-25) and chapter 20 (verses 115-127).
In these verses, the Qur'an shows that Adam was created specifically for the earth and the way to send him down was through the Garden where he was forbidden to approach a particular tree; so that eating from it would signal that he was fit for this earth, ready for this life. The issue of a sin or punishment does not arise because Adam was always intended for the earth but the question arises as to why God selected this hard way to send him down from the Garden to the earth. Allamah Tabataba'i says that in this process, he attained to such heights of eternal bliss and spiritual perfection as it would have been impossible to reach without coming down to the earth – and that too after disobeying an amr irshadi (advisory command).
In this discussion, it would be worthwhile to include two very important points mentioned in al-Mizān regarding the story of Adam:
First: Pondering over the story of Adam in the Qur'an, one will find that God had issued two decrees in respect of Adam and his descendants. First, that he should get down on the earth (after partaking from the tree) and spend his life therein – a life full of trouble and toiling. Second, it was ordained that he and his descendants should be honored with guidance (after he turned to God). Tabataba'i says that the first decree initiated the earthly life for him; the second one bestowed dignity and grace to that life, by providing it with divine guidance. From then on, man's life is composed of two lives: A material, earthly life and a spiritual, heavenly one.
Second: The events leading to his removal from the Garden and, later, to the acceptance of his turning (towards God) showed him his true reality – how humble, dependent and deficient he was; and at the same time he came to realize that every difficulty of this world leads to manifold ease in the next life; every unpleasantness here results in enhanced pleasantness there; every trouble in the obedience to God brings in its wake the pleasure of God and His unlimited reward; the process continues until the servant reaches the sublime presence of his Lord. Adam knew, through his own experience, the taste of many of the beautiful attributes of God: His forgiveness, turning mercifully to the servants, covering their mistakes, bestowing mercy on them, putting them in the shadow of His compassion and grace - these are some of the divine attributes which He has especially reserved for the sinners. Adam could not know and understand them without passing through the stages which God had decreed for him.
Poser: One wonders about the basis for the distinction made between disobedience to an amr irshadi (advisory command) and disobedience to an amr mawlawi (authoritative command), as well as how the former type of disobedience is not reprehensible.
Reply: The command given to Adam not to approach a particular tree was of the advisory nature because at the time when Adam partook from that tree, no shari'ah was ordained yet and no law was promulgated. Therefore, whatever Adam did was not a transgression against any law of the shari'ah, nor was there any sin or mistake involved in acting against that advice.
Reference: al-Mizān English Volume 1, pp. 179-191, first edition, WOFIS, 1986