The late Allamah Syed Mohsen Amili, the writer of A'yan al Shi'a says: Hesham has written the book- Al-Alfaz. So the statement of Jalaluddin Seuti: that the first writer of the fundamentals of Muslim laws, according to the consensus of scholars, is Shafei, "is not correct, because Hesham b. Hakam has been living a very long time before him. Moreover to emphasize this point it is known that Imam al-Baqer [a] and Imam al-Sadiq [a] used to teach the complete and useful rules of this science from the chapters of etymological arguments and rational proofs to their pupils and followers. A group of scholars have also compiled a few books regarding the traditions quoted from the holy Imams on this very topic.
Furthermore, the respected Allamah also mentions the names of some of the great scholars to prove that Hesham is the first man who has written books on the topic of the science of the fundamentals of speculative theology. Hesham was well informed of the different topics of the fundamentals. Beliefs, philosophical (Divine Metaphysics) discourses and Muslim laws. He was also well-versed in argumentation about the Creator, unity of God, attributes of His Glory and Beauty and God's will. He was expert at reasoning for Imamate (leadership) and Wilayah, knowledge, chastity, all other qualities of the Imams and also regarding miracles and unusual actions of those pious men. He was well acquainted with the Qur'an, the words of God and the discussion on free will and freedom of human beings. Likewise, he was well versed in the topics of the atom and metaphysics, the materiality of some matter, the reality of human beings, cause of earthquakes, rain and etc., in natural philosophy.