Sahih al-Bukhari 3506
Sahih al-Bukhari · Book 61: Virtues and Merits of the Prophet (pbuh) and his Companions · The Qur'an was revealed in the language of Quraish
Narrated Anas:
حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ عَبْدِ اللَّهِ ، حَدَّثَنَا إِبْرَاهِيمُ بْنُ سَعْدٍ ، عَنِ ابْنِ شِهَابٍ ، عَنْ أَنَسٍ ، أَنَّ عُثْمَانَ، دَعَا زَيْدَ بْنَ ثَابِتٍ وَعَبْدَ اللَّهِ بْنَ الزُّبَيْرِ وَسَعِيدَ بْنَ الْعَاصِ وَعَبْدَ الرَّحْمَنِ بْنَ الْحَارِثِ بْنِ هِشَامٍ فَنَسَخُوهَا فِي الْمَصَاحِفِ، وَقَالَ عُثْمَانُ لِلرَّهْطِ الْقُرَشِيِّينَ الثَّلاَثَةِ إِذَا اخْتَلَفْتُمْ أَنْتُمْ وَزَيْدُ بْنُ ثَابِتٍ فِي شَىْءٍ مِنَ الْقُرْآنِ، فَاكْتُبُوهُ بِلِسَانِ قُرَيْشٍ، فَإِنَّمَا نَزَلَ بِلِسَانِهِمْ. فَفَعَلُوا ذَلِكَ.
`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 Qur'an 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 Qur'an, then write it in the language of Quraish, as the Qur'an was revealed in their language." So they acted accordingly. (Sa`id bin Thabit was an Ansari and not from Quraish ).