English Translation
Narrated Anas bin Malik: (The Caliph 'Uthman ordered Zaid bin Thabit, Said bin Al-As, 'Abdullah bin Az-Zubair and 'Abdur-Rahman bin AlHarith bin Hisham to write the Quran in the form of a book (Mushafs) and said to them. "In case you disagree with Zaid bin Thabit (Al-Ansari) regarding any dialectic Arabic utterance of the Quran, then write it in the dialect of Quraish, for the Quran was revealed in this dialect." So they did it.
This hadith is from Sahih al-Bukhari, the most rigorously authenticated collection in Islamic scholarship. No editorial opinion is added.