The noble Qur'an has been revealed in exact words to the heart (faculties of perception) of the Prophet (s) by Gabriel, the angel of revelation from God the way it is recorded in al-Lawh al-Mahfuz. Revelation is a real and spiritual phenomenon which means sending a message from God to prophets (s), and in the case of the Qur'an, it has been revealed to the Last of Prophets (s).
'Allama Tabataba'i said, "What is understood from the Qur'an is that this divine book has been the result of the revelation given to the noble Prophet (s). Revelation is a heavenly (non-material) communication which cannot be understood neither by intellectual, nor by sensual faculty; rather it can be perceived by another type of perception which some people are granted by God and they receive orders from revelation and divine teachings unseen from the intellect and sense. And taking this responsibility is called prophethood."
According to 'Allamah Tabataba'i, the common belief among Muslims about revelation of the Qur'an, which has been originated from the appearance of the Qur'an, is that the verses of the noble Qur'an are the very words of God which have been revealed to the noble Prophet (s) by one of the closest angels to God. The name of that angel is Gabriel or "Ruh al-Amin" who delivered the words of God to the noble Prophet (s) during 23 years and this way the Prophet (s) was missioned to recite those words to people and teach them their meanings and invite them to ideological teachings, social and civil regulations and individual duties to which the Qur'an calls the people.
According to Ramyar, the reality of revelation to prophets (s) has been frequently narrated during history and has been approved by their companions (and even their enemies), even though there are many disagreements about its explanation and justification.
Nuzul (Descent or the Process of Revelation)
Nuzul of the noble Qur'an is delivering messages from the origin of the revelation (God) to its destination (the heart of the Prophet (s)) during 23 years since Laylat al-Qadr, one of the nights in the last ten days of Ramadan in the first year of Bi'tha (the beginning of the Prophet's (s) mission) until a short time before the Prophet (s) passed away. When the revelation of the noble Qur'an, is mentioned as an act of God, it is called "Inzal" and "Tanzil".
The first Sura revealed to the Prophet (s) is al-'Alaq (also known as "Iqra'" because of its first verse). Some have said that at the beginning, only the five verses of this sura were revealed. Also, some other scholars believe that the first complete sura which was revealed to the Prophet (s) was Fatihat al-Kitab (Sura al-Hamd).
The last sura revealed to the Prophet (s) was Sura al-Nasr. Some Quranic researchers have said that the Qur'an was at once descended from al-Lawh al-Mahfuz to Bayt al-'Izza or al-Bayt al-Ma'mur (in the fourth sky) in Laylat al-Qadr and then during 23 years was descended and revealed to the Prophet (s).
Mulla Muhsin Fayd al-Kashani said, "These two kinds of revelation, both mean the revelation of the Qur'an's meaning to the heart of the Prophet (s)… Then every time Gabriel appeared to him and brought revelations during the 23 years, he recited the words for the Prophet (s), and then they would come from inside the heart of the Prophet (s) to his tongue."