The learned scholar Tabatabai has explained it in detail in...
The learned scholar Tabatabai has explained it in detail in his precious book [^4] and a gist of it is given below: The real and actual purpose of the Holy Qur'an saying that: We revealed it in the month of Ramadan is that it was revealed to the Holy Prophet during that month, because besides being revealed in parts the Holy Qur'an possesses a reality about which Almighty Allah informed His great Messenger in a particular night of the month of Ramadan.
As the Holy Prophet possessed knowledge of the entire Holy Book, he was directed not to make haste in divulging its contents and to wait till he received orders regarding its communication to the people gradually. The Holy Qur'an says: Do not make haste in narrating the contents of the Qur'an till you receive orders in this behalf through revelation.
This reply shows that the Holy Qur'an possesses a total existence which was revealed in its entirety at one time in the month of Ramadan and it also possesses a gradual existence which lasted from the day of the Holy Prophet's appointment to the prophetic mission up to the end of his life. The Third Reply As has been explained briefly regarding the different kinds of revelation, it has evidently various stages. The first stage is that of true visions and dreams.
The second stage is that of oracular and heavenly voices which are heard without facing an angel. And the last stage is that when the Prophet sees an angel and hears the words of Allah from him and learns through him about the realities of other worlds.
As the human soul does not possess the requisite strength to bear the different stages of revelation in the very first instance, it is necessary that the capacity to bear them should develop gradually, it may be said that: on the day of his appointment to the prophetic mission (27th of Rajab) and for some time thereafter the Holy Prophet heard only those Heavenly voices which informed him that he was the Messenger and Prophet of Allah and no verse was revealed during that period.
And some time later gradual revelation of the Qur'an began in the month of Ramadan. By this we mean that the appointment of the Prophet to the prophetic mission in the month of Rajab is not attached to the revelation of the Qur'an in that month. In view of this there should be no discrepancy between the Qur'an being revealed in the month of Ramadan and the Prophet being appointed to the prophetic mission in the month of Rajab.