It is obligatory to have faith in all that has been conveyed by the Holy Prophet and the Imams including what they have said about the Prophethood of the past Prophets, about the revealed Books, the existence of the angels, the account of what is going to happen in the grave, its punishment and its reward, revivification, its horrors, reckoning, the 'balance', the path, speaking of the limbs and organs, the existence of the Paradise, the Hell and the Fountain (a reservoir of nectar in Paradise) from which Imam Ali, Amirul Mu'minin will give water to the thirsty to drink on the Day of Resurrection, intercession of the Holy Prophet and the Imams on behalf of those who loved them out of the perpetrators of grave and deadly sins. The infallible Imams and the Holy Prophet have told us about all these things.
source : http://www.islamicecenter.com/e-library/logic_islamic_rules/logic_islamic_rules_makarem_subhani_03.html
