Imam is the custodian of Prophet, he may be regarded as representative of Prophet. In the absence/ any controversy, he has to explain true Islamic Jurisdiction, because he has got knowledge of Prophet, he has the knowledge, gifted by Prophet, whereas, Prophet has be bestowed all, including knowledge by Almighty Allah.
Allah has comprehensive programme for Hidayat, through Prophets and their representative. The representation of Prophet exits every time, until Qiyamat
