Abu Dawud said: Abu Ishaq told that Ali looked at his son al-Hasan and said: This son of mine is a sayyid (chief) as named by the Prophet ﷺ, and from his loins will come forth a man who will be called by the name of your Prophet ﷺ and resemble him in conduct but not in appearance. He then mentioned the story about his filling the earth with justice.
Narrated Ali ibn Abu Talib: The Prophet ﷺ said: A man called al-Harith ibn Harrath will come forth from Ma Wara an-Nahr. His army will be led by a man called Mansur who will establish or consolidate things for Muhammad's family as Quraysh consolidated them for the Messenger of Allah ﷺ. Every believer must help him, or he said: respond to his sermons.