`Uthman called Zaid bin Thabit, `Abdullah bin Az-Zubair, Sa`id bin Al-`As and `AbdurRahman bin Al-Harith bin Hisham, and then they wrote the manuscripts of the Holy Quran in the form of book in several copies. `Uthman said to the three Quraishi persons. " If you differ with Zaid bin Thabit on any point of the Quran, then write it in the language of Quraish, as the Quran was revealed in their language." So they acted accordingly. (Sa`id bin Thabit was an Ansari and not from Quraish ).
Sahih al-Bukhari Book 61, Hadith 16