Transmission of Quranic Sciences to the Infallible Imams
The honorable Messenger of Islam (s) attempted to teach Quranic sciences and teachings as well as exegesis of the verses to Imam Ali (`a) to be left for later Muslims. Imam Ali (`a) recorded this information exactly and transmitted to other Imams (`a). Therefore, all infallible Imams (`a) can be considered knower of Quranic exegesis and truth and pioneers in Quranic sciences, as was Prophet Muhammad (s). The difference, however, was that the Prophet (s) received the revelation –and Quranic sciences– directly, while the Imams (`a) acquired the sciences through Prophet Muhammad’s (s) guidance and Allah’s especial attention –which is a key necessity for being an Imam.
In sum, the Holy Quran is a major source of infallible Imams’ sciences and the Imams (`a) are knower of Quranic sciences and exegesis, as is mentioned in many traditions.
Abus Sabah says, “By Allah that Imam Baqir (`a) stated, ‘The Almighty Allah taught Quranic sciences and exegesis to His Prophet (s). The Prophet (s) taught them to Ali (`a). By Allah that Ali (`a) taught them to us.’”
Imam Sadiq (`a) said, “I know Allah’s Book by heart completely. The news of heaven and the earth from the past to the future are in it. The Almighty Allah stated, ‘Everything is mentioned in the Quran.’”
Barid Ibn Mu’awiyyah has narrated Imam Sadiq (`a) or Imam Baqir (`a) who said about the Quranic verse,
وَما يَعْلَمُ تَأْوِيلَهُ إِلّا اللَّهُ وَالرّاسِخُونَ فِى العِلْمِ
(no one knows its hidden meanings except God and those who are firmly grounded in knowledge), “The Messenger of Allah (s) was the best pioneer in science. The Almighty Allah taught him whatever He had revealed to other prophets (s) in addition to their exegesis, not leaving anything untold. The Prophet’s (s) successors know all these too. Those who are now aware of Quranic exegesis say that they believe in what Allah has revealed when they hear it from a scholar (Prophet’s successor). The Holy Quran has absolute and conditional, cancelling and cancelled, and specific and general verses. Pioneers in science know them all.” 
Abdur Rahman Ibn Kathir has quoted from Imam Sadiq (`a), “The pioneers in science are Amiral Mu’minin (`a) and the Imams (`a) after him.”
The mentioned traditions and many other similar ones indicate that the infallible Imams (`a) knew Quranic exegesis, the scientific sources, the real advantages and reasons for issuing religious commandments and rules, just like Prophet Muhammad (s). The difference, of course, was that the Prophet (s) received the revelation directly, while infallible Imams (`a) were deprived of it. Therefore, what was mentioned about the commandments issued by the Prophet (s) is true about the commandments issued by the Imams (`a), which are not seen in Holy Quran and Prophet’s (s) tradition. In other words, they are issued by the Imams; they were allowed to issue verdicts because of their known purified conduct. And Allah knows best.
 Jami’ Ahadith Al-Shi’ah, Vol 1, p. 184.
 Kafi, Vol 1, p. 229.
 Surah ‘ali ‘Imran(3) 7: .
 Kafi, Vol 1, p. 113.
 Usul Kafi, Vol1, p. 213.