Needless to say, the Qur’an is the most important source for all Muslims, including the Shi‘a. The Qur’an also acts as an instrument of unity among all Muslims. Regardless of their different sectarian and cultural backgrounds, all Muslims refer to the same Book as the divine guide to govern their life. Today, as in any other time, there exists only one Qur’an, without any addition or alteration, throughout the Muslim world. A typical Shi‘a standpoint towards the Qur’an can be found in the following passage:
We believe that the Qur’an was divinely inspired, and revealed by Allah on the tongue of His honorable Prophet, making clear everything, an everlasting miracle. Man is unable to write anything like it because of its eloquence, clarity, truth and knowledge, and no alteration can be made to it. The Qur’an we have now is exactly what was sent to the Prophet, and anyone who claims otherwise is either an evil-doer, a mere sophist or else a person in error, and all of them have gone astray, because it is the speech of Allah, and: “Falsehood cannot come at it from before it or from behind.” (41:42)
…We also believe that we must respect and give dignity to the Glorious Qur’an, and this both in word and in deed. Therefore, it must not be defiled intentionally, not even one of its letters, and it must not be touched by one who is not tahir [i.e. ‘pure’]. It is said in the Qur’an: “None can touch it save the purified.” (56:79)1
1 Muzaffar, The Faith of Shi‘a Islam, p. 26.
Discovering Shi’i Islam Mohammad Ali Shomali 9th edition