The Qur'an is the Book of Allah Who sent it down as a Revelation to His Prophet Muhammad (s.a.w.).
Allah protected it (the Qur'an) against any distortion, forgery and disfigurement, additions and deletions.
Praise be to Allah that all the Muslims agree with the purity and the safety of the Qur'an, but there is a scientific problem which is the problem of understanding the Qur'an and its explanation. Most of the differences in ideological, and jurisprudental opinions belong to the difference that exist in understanding and explaining the Qur'an.
In order to give a correct explanation to the Qur'an, the Imams of Ahlul-Bait (a.s.) used to follow a scholarly method in explaining the Qur'an, these are:
1. The explanation of the Qur'an by the Qur'an,
that is; some Qur'anic verses explain some others.
2. The explanation of the Qur'an by true and authentic traditions and narrations. Surely the Messenger of Allah (s.a.w.) explained what was in need of explanation through his sayings and actions, like the verses of prayer, paying the poor-rate (zakat), pilgrimage and various other Qur'anic concepts and laws.
3. Explaining the verses, whose explanation does not reach us from the pure Prophetic traditions (sunnah), and were not clear, because of other verses, from the linguistic understanding of the Arabic language. Indeed Allah's Book is a clear Arabic Book; what is understood from its literal meaning is an excuse upon the Muslims.
4. The explanation depends on the reason for the revelation in explaining most of the verses of the Qur'an and this should be done within the framework of the Qur'an and the Traditions in order to give their true and real meanings.