Sacred texts

Literally the speech of God, written in Arabic. Its composition is divine origin and revelation, with the Prophet Muhammad as messenger not author.

Because the actual Arabic words are imbued with sacredness, which gives importance to the act of recitation. A Qur'an in another language is regarded solely as a translation.

That it was collated during the Prophet Muhammad's lifetime, or during Caliph 'Uthman.

Different contexts changed the emphasis of themes — the Day of Judgment in Meccan suras, and umma in Medinan suras.

The sayings and deeds of the Prophet Muhammad and his companions — and, for Shias, the sayings of the imams. The guide's word for their standing is inspiration.

Authenticity and historicity of the main collections, and the existence of additional Shi'i Hadiths.

The science of interpretation or exegesis of the Qur'an. Commentary has to observe certain rules or conditions, for example as proposed by the exegete Dehlavi.

Islam: the Arabic words are God's speech, so a translation is solely a translation. Judaism: Hebrew is the sacred language, with the translation printed opposite. Christianity: translated into the vernacular from the start, with several versions.

Because the Qur'an commands practices such as salat without setting out how they are performed; the Sunna of the Prophet, transmitted through the Hadith, supplies that.