Holy Prophet (sawa) said, “Surely the Khulafa, successors and Hujjatullah (proofs of Allah) upon the creation after me are 12, the first of whom is my brother and the last one is my son. It was asked: O prophet of Allah (sawa), who is your brother? He replied, Ali Ibn Abi Talib. Then it was asked, who is your son? The Holy Prophet (sawa) replied, It is Mahdi who will fill the earth with equity...