I have read in Wikipedia that some Shia Muslims disputed the canonical validity of the Uthmanic codex of the Quran. Is this true? If so, can you tell me who they were?
Shia believe that Quranic text is intact and no one can change it as Allah (SWT) promised in Quran (We Have revealed the Thikr (Quran) and We Are keeping it intact) Sura 15, Verse 9.
Uthman removed he Tafseer which was mentioned by the Prophet Muhammad (SAWA) on some verses and written by Imam Ali (AS). The Quranic text remains the same.
Wassalam.