Prophet Muhammad “peace be upon him,” said

O people! The straight path God commanded me, that you have to follow it. And after me ‘Ali is and then children of his generation, the leaders of the Rastnd that the truth and the judgment and invite Rahnmaynd.
tip:
Because the Prophet PBUH and prophet knew after he diverted flow and the snare of the evil will continue, hence the recognition criteria established in the first step to the right and straight path, confirm their existence, he said. Path that one can not doubt it into Sazd.sps bid: the straight path after me Ali

Seen in “The robe Ghadir", Page 64.