The immediate revelation of the Holy Quran upon the blessed heart of the Holy Prophet (s) happened on the Night of Qadr (one of the nights of the Holy Month of Ramadhan). By referring to some of the traditions and their context, the possibility becomes strengthened that the Night of Qadr is the twenty third night of the Month of Ramadhan and the immediate revelation of the Holy Quran took place approximately 56 days after the bi’thah (the day when the Prophet was appointed on his mission). The particularities of the gradual revelation of the Holy Quran have many conflicting reports and it seems that two reports have more importance than the rest. These are:
1. The gradual revelation of the Holy Quran occurred at the same time as the Bi’thah and continued till the end of the life of the Holy Prophet (s). According to the most authoritative opinion it is said that the Holy Prophet (s), during the 27th of Rajab, which coincided with the month of February of the year 610 (A.D.), came upon the mission of his prophet hood and during the 28th of the month of Safar, during the 11th year of Hijra, he passed away from this world.
2. Although a few verses from the Holy Quran were revealed when the prophet (s) was appointed to his mission, but the gradual revelation in the form of a divine book took place three years after the Bi’thah. It started from the Night of Qadr and continued until the end of the life of the Holy Prophet (s). Hence, by paying attention to the fact that we are currently in the month of February during the year 2007 (AD), we can count the number of years that have passed since the gradual revelation of the Holy Quran.
We know that the immediate revelation of the Holy Quran took place on the Night of Qadr and the Holy Quran says about this matter that: The month of Ramadhan is the month in which the Quran was revealed. Therefore, the Night of Qadr is situated in this holy month. There isn’t exact certainty as to the night which the Night of Qadr is on and there are conflicting ideas as to when the exact date falls on. It seems that amongst all the various possibilities, the strongest possibility is that the night falls on the 23rd of the Month of Ramadhan; many traditions and clues in them emphasize this possibility.
It is not clear on which year this blessed event occurred, however it can be said that although the night of Qadr was the night when the Holy Quran was revealed in the material world, it was also the night when the Prophet (s) ascended into the heavens. The reason being that the Quran lies in the Ummul-Kitab, which is with the Lord, and as long as one doesn’t ascend he cannot retrieve the Quran that lies therein. From this point it can be understood that the immediate revelation of the Holy Quran occurred at the time when the Holy Prophet (s) reached this stage of perfection. Hence, we give it a strong possibility that the revelation took place during the first year of the prophetic mission. This would make it approximately 56 days after the Bi’thah. This number was calculated by taking into account the time of the Bi’thah (27th of Rajab), the Night of Qadr (23rd of the Month of Ramadhan), and by estimating the Months of Sha’baan and Rajab as being 30 days each.
In respect to the gradual revelation of the Holy Quran, which happened at the same time as the Bi’thah, it becomes subject to difference of opinion due to the debate over the exact date of the actual Bi’thah.
The most famous opinion is that the Holy Prophet (s), on Wednesday of the 27th of Rajab (which is the first of February of the year 610 (A.D.), was commissioned on his mission of prophethood. When this occurred the first five verses of Surah Alaq were revealed to the Holy Prophet (s). After this the revelation the Quranic verses were gradually revealed until the time of the passing of the Prophet (s); this took place over a span of 23 years.
A group of Muslims believe that there is a difference with the time of the Bi’thah compared with the time of the gradual revelation of the Holy Quran (in the form of a divine book). According to their opinion, even though five verses were revealed from Surah Alaq at the time of the Bi’thah, the Holy Prophet (s) was still not commissioned to publicly preach. Only after three years of secret teaching was he commissioned to publicly preach Islam, It was from this that the Holy Quran was compiled into the form of a divinely inspired manuscript. From this perspective even if the Bi’thah occurred in the month of Rajab, still the start of the gradual revelation of the Holy Quran occurred after three years during the night of Qadr in the month of Ramadhan.
There are traditions that confirm this idea by stating that the time of the revelation of the Quran was over a period of 20 years. Hence this idea and theory states that the time of the gradual revelation of the Holy Quran (in the form of a divine book) took place during the 4th year of the Bi’thah. If we calculate this it will end up being approximately 3 years and 56 days after the Bi’thah of the Holy Prophet and it continued till the Prophet’s (s) passing (he died on the 28th of Safar on the 11th year of the Hejrat).
In conclusion, 1428 years have passed since the time of the migration of the Holy Prophet (s) and the Bi’thah was approximately 13 years before that. If we accept the first idea, then from the time of the first verse that was revealed approximately 1440 (Qamari) lunar years have passed. If we accept the second idea then from the time of the revelation of the first verse, 1437 years have elapsed.
Let it not be left unsaid that according to the reports from some historians, the time of the Bi’thah occurred at the first of February during the year 610 A.D. If we calculate the fact that we are currently in the year 2007 A.D. we can calculate the time from the revelation of the first verse according to this.
 Dukhan:3, Qadr:1. For further information, see: Al-Mizan, vol. 8, pp. 130-134; vol. 2, pp. 14-23; vol. 13, pp. 220-221.
 See: Tarikh Tabari, vol. 2, pg. 300; Sirah Ibn Hisham, vol. 1, pp. 236 and 239 and 240; Ayatullah Ma’rifat, Al-Tamhid fi Ulumil-Quran, pp. 100-129; Ayatullah Khu’i, Al-Bayan, vol. 1, pg. 224; Majma’ul-Bayan, vol. 9, pg. 61 and vol. 10, pp. 518-520; Tarikh Abil-Fada’, vol. 1, pg. 115; Tarikh Ya’qubi, vol. 2, pg. 17; Sheikh Tusi, Al-Tibyan, vol. 9, pg. 224; Tabari, Jame’ul-Bayan, vol. 25, pp. 107 and 108; Al-Mizan, vol. 2, pg. 29.
 Wasa’elul-Shia, chapter 32 of the chapters on the month of Ramadhan, vol. 7, pg.262, hadith 16; Khisal of Saduq, vol. 2, pg. 102; Muhammad Baqir Hujjati, Pajouheshi dar Tarikhe Qurane Karim, pp. 38-62.
 See: Ayatullah Javadi Amoli, Tafsir Mozu’i, vol. 3, pp.139-153.
 Isra:106; Furqan:32; Muhammad:20; Tawbah:127; for further information, refer to Al-Mizan, vol. 2, pp. 14-23.
 Tarikh Ya’qubi, vol. 2, pg. 17; Tarikhul-Khamis, vol. 1, pp. 280 and 281; Tarikh Abil-Fada’, vol. 1, pg. 115.
 Pajouheshi dar Tarikhe Qurane Karim, pg. 36; Bihar, vol. 18, pg. 189, hadith 21; Furu’ul-Kafi, vol. 4, pg. 149, hadiths 1 and 2; Wasa’ilul-Shia, vol. 7, pg. 329, chapter 15 of the chapters on mustahabb fasting; Al-Siratul-Halabiyyah, vol. 1, pg. 238; Al-Tamhid fi Ulumil-Quran, pp. 100-107.
 Biharul-Anwar, vol. 18, pg. 206, hadith 36.
 Hijr:94; Tafsir Qummi, pg. 353; Bihar, vol. 18, pg. 53, hadith 7 and pg. 179, hadith 10 and pg. 177, hadith 4 and pg. 193, hadith 29, translation of Ayati, vol. 1, pg. 379; Tarikh Yaqubi, vol. 1, pg. 343; Siratu ibn Hisham, vol. 1, pg. 280; Al-Manaqib, vol. , pg. 40; Sheikh Tusi, Al-Gheybah, pg. 217.
 See: Majma’ul-Bayan, vol. 2, pg. 276; Al-Itqan, vol.1, pg. 40; Tafsir Kabir Imam Razi, vol. 5, pg. 85; Al-Manaqib, vol. 1, pg. 150; Sheikh Mufid in his commentary on Saduq’s Aqa’id, pg. 58; Seyyid Murtada in his response to Al-Masa’ilul-Trablusiyyat Al-Thalathah, pp. 403-405.
 Al-Usul minal-Kafi, vol. 2, pg. 628, hadith 6; Tafsir Ayyashi, vol. 1, pg. 80, hadith 184; Saduq, Al-I’tiqadat, pg. 101; Bihar, vol. 18, pg. 250, hadith 3, and pg. 253; Al-Itqan, vol. 1, pp. 40-45; Tafsir Shubbar, pg. 350; Mustadrakul-Hakem, vol. 2, pg. 610; Asbabul-Nuzul, pg. 3; Al-Bidayah wal-Nihayah, vol. 3, pg. 4; Tarikh Yaqubi, vol. 2, pg. 18.
 For further information, refer to the book: Al-Tamhid fi Ulumil-Quran, pp. 100-129.