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Contributions to Islamic sciences

The standard recitation of the Quran has been traced back to Ali, and his written legacy is dotted with Quranic commentaries. Ibn Abbas, a leading early exegete, credited Ali with his interpretations of the Quran. Ali also related several hundred prophetic hadiths. He is further credited with the first systematic evaluations of hadiths, and is often considered a founding figure for hadith sciences. Ali is also regarded by some as the founder of Islamic theology, and his sayings contain the first rational proofs of the unity of God (tawhid) in Islam. In later Islamic philosophy, Ali's sayings and sermons were mined for metaphysical knowledge. In particular, Nahj al-balagha is a vital source for Shia philosophical doctrines, after the Quran and Sunna. As a Shia imam, statements and practices attributed to Ali are widely studied in Shia Islam, where they are viewed as the continuation of prophetic teachings.