'at the time when the messenger of Allah (s.a.w.a.) was departing from this world, i went in his presence. he narrated for me a tradition where he concluded it as such: 'o fatemah, i swear by the lord who appointed me by the truth that Mahdi of this nation shall be from hassan and hussein.
Allah shall send Mahdi at the time when the world will fall into chaos. when seditions will prevail; when means will be cut-off; when some will revolt over the other; when there will remain no elder who will have mercy upon the young and when there will remain no young who will respect the elders. Mahdi shall conquer the forts of deviation and depravity and she afted hearts. Mahdi shall rise for the religion at the end of time just as i rose for it in the beginning. he shall fill the world with justice as it was filled with oppression.
'during Mahdi's time red and white death and locuts will become visible. otherwise too red coloured locusts will be found. red death refers to the sword and white death refers to plague.
in the same section and same chapter of the afore-said book, its author narrates from 'sunan' of imam abu amro uthman-ibn- saeed muqarri and 'fatan' of hafiz abu-abdullah na'eem-ibn - hemaad a tradition from amir-ul-mumineen ali-ibn - abi talib (a.s.) as such: 'Mahdi shall not emerge until out of three persons one gets killed, the other dies and the third remains.'
thereafter Allah will appoint a man from my ahl-e-bayt who will fill the earth with equity and justice just as it was previously filled with cruelty and tyranny....
the author of 'eqdud-durar' in section one, chapter four has narrated from imam muhammad baqir (a.s.) as such: of 'Mahdi shall not emerge but after prevalence serve awe amongst the people, when people will be afflicted with earthquakes and plagues, when strife and discord will emerge amongst the people, when differences in religion will prevail amongst them, when people's condition will so change that they would wish for death, day and night.... Mahdi shall emerge at the time of hoplessness and despair. blessed is he who perceives Mahdi and joins the rank of his helpers. woe be to the one who opposes him and his commands.