..By Allah, if he (Abu Bakr) had ordered me to shift one of the mountains it would not have been harder for me than what he had ordered me concerning the collection of the Qur'an... So I started locating the Qur'anic material and collecting it from parchments, scapula, leafstalks of date palms and from the memories of men.[Bukhari Sahih al-Bukhari, 6:60:201]

He also said:

"So I started looking for the Holy quran and collected it from (what was written on) palm-leaf stalks, thin white stones, and also from men who knew it by heart, until I found the last verse of Surat at-Tauba (repentance) with Abi Khuzaima al-Ansari, and I did not find it with anybody other than him. (Sahih al-Bukhari, Vol.6, p.478).

The task required ibn Thabit to collect written copies of the Qur'an, with each verse having been validated with the oral testimony of at least two companions. Usually the written copies were verified by himself and Umar - both of whom had memorized portions of the Qur'an. Thus, eventually the entire Qur'an was collected into a single copy, but it still wasn't given any particular order.[27]

This compilation was kept by the Caliph Abu Bakr, after his death by his successor, Caliph Umar, who on his deathbed gave them to Hafsa bint Umar, his daughter and one of Muhammad's widows.[27]
Uthman ibn Affan and the Canonization

The Qur'anic canon is the form of the Qur'an as recited and written in which it is religiously binding for the Muslim community. This canonical corpus is closed and fixed in the sense that nothing in the Qur'an can be changed or modified. The process of canonization ended under the third caliph, Uthman ibn Affan (r. 23/644–35/655), which was about twenty years after the death of the Prophet.[29]

By the time of the caliphate of Uthman ibn Affan, there was a perceived need for the compilation of the Qur'an. The Caliphate had grown considerably,expanding into Iraq, Persia, Egypt and Iran, bringing into Islam's fold many new converts from various cultures with varying degrees of isolation.[30] These converts spoke a variety of languages but were not well learned in Arabic and so a complete written text of the Qur'an had to be compiled. Another reason for compiling the Qur'an was that many of the Muslims who had memorized portions of the Qur'an were dying, especially in battle.

According to the dominant version narrated by Sahih al-Bukhari, the reason for the final collection of the Qur'an was a dispute between Muslim forces from Iraq and Syria over the correct way of reciting it during communal prayers while on an expedition to Armenia and Azerbaijan.[3]

It is believed that the general, Ḥud̲h̲ayfa b. al-Yaman, reported this problem to the caliph and asked him to establish a unified text. According to the history of al-Tabari during the expedition there were 10,000 Kufan warriors, 6,000 in Azerbaijan and 4,000 at Rayy.[31] If there was disagreement amongst such a vast number of soldiers on the correct way of reciting the Qur'an, it is understandable why Ḥud̲h̲ayfa b. al-Yaman pushed for a unified text. An example of the confusion at this time is seen during a campaign in Tabaristan, where one of the soldiers asked, Ḥud̲h̲ayfa “How did the Messenger of God pray?” Ḥud̲h̲ayfa told him the soldier prayed before fighting.[32]

It is believed upon Ḥud̲h̲ayfa’s request ʿUt̲h̲mān obtained the sheets of the Qur'an from Ḥafṣa and appointed a commission consisting of Zayd b. T̲h̲ābit and three prominent Meccans, and instructed them to copy the sheets into several volumes based on the dialect of Qurays̲h̲, the main tribe of Mecca.[3]

Uthman's reaction in 653 is recorded in the following:

"So 'Uthman sent a message to Hafsa saying, "Send us the manuscripts of the Qur'an so that we may compile the Qur'anic materials in perfect copies and return the manuscripts to you." Hafsa sent it to 'Uthman. 'Uthman then ordered Zaid bin Thabit, 'Abdullah bin AzZubair, Said bin Al-As and 'AbdurRahman bin Harith bin Hisham to rewrite the manuscripts in perfect copies. 'Uthman said to the three Quraishi men, "In case you disagree with Zaid bin Thabit on any point in the Qur'an, then write it in the dialect of Quraish, the Qur'an was revealed in their tongue." They did so, and when they had written many copies, 'Uthman returned the original manuscripts to Hafsa. 'Uthman sent to every Muslim province one copy of what they had copied, and ordered that all the other Qur'anic materials, whether written in fragmentary manuscripts or whole copies, be burnt. Said bin Thabit added, "A Verse from Surat Ahzab was missed by me when we copied the Qur'an and I used to hear Allah's Apostle reciting it. So we searched for it and found it with Khuzaima bin Thabit Al-Ansari. (That Verse was): 'Among the Believers are men who have been true in their covenant with Allah.'"[Quran 33:23][Bukhari Sahih al-Bukhari, 6:61:510]