The fact that Uthman burnt up all other copies of the Qur’an...

The fact that Uthman burnt up all other copies of the Qur’an, and ordered his emissaries to do away with all the copies other than the codex prepared by himself, is an ample proof that there existed some difference between his copy and the others, else he would not have asked for their destruc­tion. In fact, some of the scholars have recorded those differences, like Abdullah b. Abi Dawud as‑Sajistani who wrote a book titled: Kitabul Masahif.

It could be inferred that some interpolation had occurred, either on the part of Uthman or on the part of the scribes who prepared their copies. But we will soon establish that the copy of Uthman was actually the one already known to the Muslims. It was the one which was handed over from the Prophet (‘s) and widely used. The Tahrif by way of addition or omission had occurred in those copies which ceased to exist after the era of Uthman.

As for the existing Qur’an, it is totally free from any omission or addition. In short, those who rightly believe that those extra codices of the Qur’an were not authenticated by tawattur, that is to say that their authenticity was not established by wide currency and acceptance among Muslims, for them it is also right to believe that this sort of tampering had occurred in the beginning, but it ceased to exist after the time of Uthman.

This leads us to believe that only that Qur’an remained authentic which was supported by a continuous chain joined with the Prophet (‘s). Those who hold that all the codices, despite their variations, were based on tawattur , will have to subscribe to the disputed view that Tahrif has occurred in the Qur’an, and that some parts of it is lost. Tabari has classified, as you have noticed earlier, that Uthman dismissed the six variations of reading, and allo­wed only one to sustain.

The fourth meaning of Tahrif is addition or suppression of an ayah or a Surah , at the same time preserving the revealed Qur’an intact, and accepting the fact that the Prophet (‘s) recited it as a part of the Qur’an. And this has definitely occurred in the Qur’an. The "basmalah" for example, is an ayah for which Muslims unanimously hold that the Prophet (‘s) recited it before every Surah except the Surah of al‑Tawbah . Yet, among the Ulama’ of Ahlus ­ Sunnah , it is a subject of dispute.