Ali (ع) said: The holy Prophet (ص) said:
"My partners are the ones whom The Lord has brought near to Himself and me, and has revealed this verse concerning them: (O you who believe! Obey Allah and obey the Messenger) [1] until the end of the verse.
So if you fear a dispute in a matter, refer it to Allah and the Messenger and those in authority.
I said, "O Messenger of Allah Who are those in authority?"
He said, "You are the first of them." [2]
[1] Sura Nisa, verse 59.
[2] Hakim al-Haskani, Shawahid al-Tanzil, V.1, page 189.
I say: He is the first of the twelve Imams and the second of them is Hasan and then Husain until the twelveth Imam, Hazrat Mahdi (a.t.f.s.) who will fill the earth with equity and justice just as it was filled with oppression and tyranny.
The twelve Imams are the ones who the Prophet (s.a.w.a.) has emphasized to their Imamate and has come down in authentic texts. For more information, please refer to the book of Muntakhab al-Athar, Volume 1, written by this author.