status of imam ali (as) in tafsir

quran is a book of guidance and one can achieve guidance with reference to it. but as qur'an is mostly concerned with generalities and details is left to the prophet (pbuh), to understanding quran it is essential to refer to the hadith of the prophet. but because of unlimited depth of qur'an, the prophet (pbuh) could not explain all the hidden meanings of its verses, so he saw it necessary to introduce another resource for future use and understanding of quran. on this basis, and according to the hadith of thaghalain he introduced ahl al-bayt (as) as the true explaining authority of quran. ali (as) among the ahl al-bayt (as) enjoys a special status and the prophet (pbuh) acknowledged his high status among his other companions in the field of religious matters and quran interpretation. the greatest companions have also admitted this fact. so with the reference to exegesis and hadith texts one can learn his interpretive doctrines and by understanding his status in the field of quran interpretation benefit from his teachings.