Compilation of the manuscripts of the Holy Qur’an
During the time of Hazrat Abu Bakr (ra), the various manuscripts of the Holy Quran were gathered together, which he kept with himself. Then they were kept with Hazrat Umar (ra) and after him, they were in the possession of Hazrat Hafsa bint Umar (ra). During the era of Hazrat Uthman’s (ra) Khilafat, the following narration is found in regard to him acquiring these manuscripts.
Hazrat Huzayfa (ra) bin Yaman relates that he was fighting along with the people of Iraq against the Syrians for the lands in Armenia and Azerbaijan. Upon returning from there, he presented himself before Hazrat Uthman (ra). Hazrat Huzayfa (ra) was concerned owing to the difference in their reading [Qiraat] of the Holy Quran in those lands. He submitted before Hazrat Uthman (ra), “O leader of the faithful, take care of the ummah lest they begin to dispute with one another over the book of Allah just like the Jews and Christians did.”
Following this, Hazrat Uthman (ra) sent a message to Hazrat Hafsa (ra) and asked her to give the various manuscripts of the Holy Quran so that he could produce various copies of the Holy Quran from it and then those manuscripts would be returned to her. And so, Hazrat Hafsa (ra) sent those manuscripts to Hazrat Uthman (ra). Hazrat Uthman (ra) then instructed Hazrat Zaid (ra) bin Thabit, Hazrat Abdullah (ra) bin Zubair, Hazrat Saeed (ra) bin Aas and Hazrat Abdur Rahman (ra) bin Harith bin Hisham to produce copies from those manuscripts. Hazrat Uthman (ra) then told the latter three of the aforementioned companions, who were from among the Quraish, that if there was a difference [in the qiraat] in their copy of the Quran and the Quran written by Zaid, then they should write it according to the language of the Quraish for the Quran was revealed in the language of the Quraish [i.e. their dialect of Arabic]. Thus, these companions worked on this task. When the copies of the Holy Quran were completed, Hazrat Uthman (ra) returned the original manuscripts of the Holy Quran to Hazrat Hafsa (ra) and sent the various newly produced copies of the Holy Quran to various countries and instructed that if there was any other copy of the Holy Quran besides this, it should be burnt.
(Sahih al-Bukhari, Kitab Fada‘il al-Quran, Bab Jam‘ al-Quran Hadith 4986, 4987)
Allama ibn Al-Tin states that the difference between Hazrat Abu Bakr (ra) and Hazrat Uthman (ra) compiling the Quran was that Hazrat Abu Bakr (ra) compiled the Holy Quran fearing that if the huffaz-e-Quran [i.e. those who had committed the entire Quran to memory] passed away, then some parts of the Holy Quran may be lost because until then, the Holy Quran had not been compiled in one single form. Thus, Hazrat Abu Bakr (ra) compiled the Holy Quran by placing the verses in the same order as the Holy Prophet (sa) had taught the companions to memorise it. On the other hand, Hazrat Uthman (ra) compiled the Holy Quran owing to the increasing difference in the dialects of the language. People began to recite the Holy Quran according to their own dialect and style of pronunciation and would deem the reading style [qirat] of others to be incorrect. Hazrat Uthman (ra) was concerned that perhaps this would lead to a more serious situation. And so, Hazrat Uthman (ra) compiled the various manuscripts, which Hazrat Abu Bakr (ra) had initially collected, into a single copy according to the sequence of its chapters. Moreover, Hazrat Uthman (ra) kept it in the language of the Quraish and the reason he gave for doing this was that the Quran was revealed in the language of the Quraish. Although initially it was also permitted that one could recite the Quran in other dialects as well for the purpose of ease; however, when Hazrat Uthman (ra) observed that there was no longer any need to do it in this manner, he instructed for it to be recited in only one style of reading [qirat].
Allamah Qurtabi states that if the question is posed that why did Hazrat Uthman (ra) feel the need to compile the Quran and standardise it to one single reading for the people even though before him Hazrat Abu Bakr (ra) had already compiled it, then the answer to this is that Hazrat Uthman (ra) did not do this in order to compile the manuscripts. This [was already done] because Hazrat Uthman (ra) had sent a message to Umm-ul-Momineen, Hazrat Hafsa (ra) requesting for those very manuscripts of the Holy Quran so that he could produce various copies from it and thereafter he would return to her the original manuscripts. Thus, the reason why Hazrat Uthman (ra) did this was that people had started to disagree with one another over the different styles of reading [qiraat] of the Quran because the companions had travelled and settled in various cities. This was leading to a very serious situation and the differences between the people of Syria and Iraq had taken the form as described by Hazrat Huzayfa (ra).
(Ali Muhammad al-Salabi, Sirat Amirul Momineen Uthman (ra) bin Affan Shakhsiyyatuhu wa Asruh, Ch. 1 [Beirut, Lebanon: Dar al-Ma‘rifah, 2006]) pp. 232-231)