It is narrated from Hazrat Abu Saeed Khudri (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: The Day of Judgment will not be established until the world is filled with oppression and injustice. Then a man from my Ahl al-Bayt will emerge, and he will fill the earth with justice and fairness just as it was previously filled with oppression and injustice.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 11313