The Messenger of Allah ﷺ said, "The Mahdi is from me. He has a broad forehead and a prominent nose. He will fill the earth with justice and fairness as it had been filled with tyranny and oppression. He will rule for seven years."
حدثنا سهل بن تمام بن بزيع حدثنا عمران القطان عن قتادة عن أبي نضرة
قال رسول الله ﷺ المهدي مني أجلى الجبهة أقنى الأنف يملأ الأرض قسطا وعدلا كما ملئت جورا وظلما يملك سبع سنين
[Its chain of transmission is daif] Hakim narrated it, 4/557, from the hadith of Imran Qattan, with this wording, and graded it sahih according to the standard of Muslim, but Dhahabi disputed this. Qatada was a mudallis and he narrated it with "an" phrasing, and the hadith has daif corroborating narrations.