It is narrated from Hzrat Ali that:
AFTER WORSHIP OF ALLAH HAS TURNED INTO WORHSIP OF EARTYHLY DESIRES, HAZRAT MAHDI (AS) WILL COME, AND HE WILL TURN WORSHIP OF EARTHLY DESIRES INTO WORSHIP OF ALLAH. AND AFTER THE QUR’AN HAS BEEN ADAPTED TO PEOPLE’S OWN OPINIONS AND IDEAS, HAZRAT MAHDI (AS) WILL COME AND WILL ADAPT THEIR OPINIONS AND IDEAS TO THE QUR’AN. ...The Earth will give forth everything it conceals inside it and will place all its means and abundance at his disposal. AT THAT TIME, HAZRAT MAHDI (AS) WILL SHOW YOU WHAT REAL JUSTICE IS AND WHAT RESTORING THE BOOK AND THE SUNNA MEANS. 
(Nahw al-Balaga, Fayzal-Islam Edition, p. 424,425)