Hazrat Mahdi’s Looks
The Messenger of Allah (sal Allahu alaihi wa sallam) said: “The Mahdi is of me. He has a high forehead and a prominent nose. He will fill the world with fairness and justice as it was filled with wrongdoing and injustice, and he will rule for seven years.” [Abu Dawud]
Abu Ishaq narrated that Hazrat Ali (radi Allahu anhu) said while looking at his son Hazrat Hasan (radi Allahu anhu): “This son of mine is a leader, as told by Allah’s Messenger. Soon a man will be born from his descendents whose name will be the same as your Prophet’s name; he will resemble the Prophet (sal Allahu alaihi wa sallam) in his character and habits but not in his physical appearance.” Then Hazrat Ali (radi Allahu anhu) mentioned how the Mahdi would fill the earth with justice. [Abu Dawud]
Hazrat Mahdi’s period of rule is mentioned in some ahadith as being of seven years and in some ahadith as being of nine years. So it could be either seven or nine.