The Preservation of the Quran after the Prophet's Death (PBUH)

"The codification of the Quran (i.e. into a ‘book form') was done soon after the Battle of Yamama (11AH/633CE), after the Prophet's death, during the Caliphate leadership of Abu Bakr. Many companions became martyrs at that battle and it was feared that unless a written copy of the entire revelation was produced, large parts of the Quran might be lost with the death of those who had memorized it. Zaid ibn Thabit was requested by Abu Bakr to head a committee which would gather together the scattered recordings of the Quran and prepare a suhuf - loose sheets which bore the entire revelation on them [1].

To safeguard the compilation from errors, the committee accepted only material which had been written down in the presence of the Prophet himself (PBUH), and which could would have been verified by at least two reliable witnesses who had actually heard the Prophet (PBUH) recite the passage in question [2]. So the process included both oral and written verification. At that time a lot of the Prophet's (PBUH) companions memorized the entire Quran, and that would have been enough for the process to be completed. But the companions wanted the process of compiling the book of God to be a scientific method without any error. At the end of the process, the entire Quran was gathered in one book where every single verse was written after being verified that it was heard directly from the Prophet (PBUH) by at least two companions and a written copy of it was brought to the committee. Once all companions who memorized the entire Quran agreed on that compiled book (Quran), nothing a single word was added or deleted from that written copy and on top of that, for every single verse they companions memorized, a written copy of it was brought to the committee. Moreover, it the Quran was written down in the same order as it was revealed to the Prophet Muhammad (PBUH). Once completed and unanimously approved of by the Prophet's (PBUH) companions, these sheets were kept with the Caliph Abu Bakr (d. 13AH/634CE), then passed on to the Caliph Umar (13-23AH/634-644CE), and then Umar's daughter and the Prophet's widow, Hafsa [3].

Although the Quran was initially revealed in the Qurayshi (one of the Arabic tribes) dialect of Arabic to the Prophet (PBUH), it was also later (at the time of Prophet Muhammad, PBUH) revealed in seven different Arabian dialects to aid the understanding of those belonging to non-Quraysh tribes [4]. At the time of the third Caliph Uthman (23AH-35AH/644-656CE), however, the people of the regions of present-day Syria and Iraq had begun disputing over various pronunciations of some of the words of the Quran, while new Muslims in provinces outside Arabia were unsure which dialect should be learned. Uthman perceived the danger of divisions, disunity and corruption arising on the basis of different readings/dialects of the Quran which were earlier on approved by the Prophet(PBUH) [5]. He therefore requested Hafsa to send him the manuscript of the Quran which was in her safekeeping, and ordered the production of several bounded copies of it (also known as masaahif) using the Quraysh dialect. Here the dispute was not on the verses of the Quran- whether some verses are part of it or not. Everyone had the same copy of the Quran but the dispute was on the pronunciation of some verses. The copy that was compiled at the time of Abu Baker included the seven different Arabian dialects; however the copies written at the time of Uthman included only the Qurayshi dialect.

Upon completion (in 25AH/646CE), Uthman returned the original manuscript to Hafsa and sent the copies to the major Islamic provinces to replace other materials that were in circulation. He also ordered that all other extracts or copies of the Quran which differed from that undoubted "official" copy (including incomplete manuscripts and those with additional personal notes) be burnt so that the Quran would not suffer the same fate of alterations, uncertainty of authenticity and contradictory versions which characterized prior religious scriptures. This action of Uthman was unanimously approved of by the Prophet's (PBUH) companions, as evidenced in the accounts of Zaid, Mus'ab, and Ali that the companions had gathered in large numbers to witness the burning, with no one speaking out against it. Their accounts also reveal that many had openly declared their support for Uthman at the time, and how pleased they were with the measures he had taken [6]. It was therefore not the "Original" Quran that was burnt, nor a fabricated story to discredit Uthman in the eyes of the community, as some critics of Islam allege." [7] 

References

[1] Sahih al-Bukhari Vol.6, Hadith Nos.201 & 509; Vol.9, Hadith No.301

[2] Ibn Hajar al-'Asqalani, Fath al-Bari, Vol.9, p.10-11

[3] Sahih al-Bukhari, Vol.6, Hadith No.201

[4] Sahih al-Bukhari Vol.6, Hadith Nos. 513-514; Jalal al-Din Suyuti, Al-Itqan fi 'Ulum al-Qur'an, Beirut: Maktab al-Thaqaafiyya, 1973, Vol.1, p.41

[5] Sahih al-Bukhari Vol.6, Hadith No.510

[6] see Nizam al-Din al-Naysaburi, Ghara'ib al-Qur'an wa Ragha'ib al-Furqan, Cairo, 1962; Ibn Abi Dawud, Kitab al-Masaahif, p.12, in Arthur Jeffery, Materials for the History of the Text of the Qur'an, Leiden: Brill, 1937; and Badr al-Din al-Zarkashi, Al-Burhan fi Ulum al-Qur'an, Cairo, 1957, Vol.1, p.240 respectively

Source:

[7] http://www.ilaam.net/Articles/AuthenticQuran.html