The Mahdi and other just caliphs

It is narrated from Abu al-Jald (may Allah have mercy on him) that he narrated this and swore an oath on it, saying: "This Ummah will certainly not perish until twelve caliphs have passed in it, all of whom will act according to guidance and the religion of truth. Of these twelve, two men will be from the household (Ahl al-Bayt) of the Prophet (peace and blessings be upon him); one of them will live (managing the affairs of the caliphate) for forty years and the other for thirty years. And after them there will also be caliphs who will not be on the way of those (rightly guided caliphs)."
Imam Musaddad bin Musarhad recorded this narration in his Musnad. Its narrator is Abu al-Jald Jaylan bin Jami' al-Basri, a trustworthy (thiqah) Successor who was an expert in the knowledge of the earlier scriptures; for this reason he swore an oath on this prophecy, which in his view was established from his study of the earlier revealed books.

It is narrated from Sayyiduna Qurrah bin Iyas al-Muzani (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "This earth will be filled with oppression, tyranny and injustice. Then, when it is completely engulfed in oppression and tyranny, Allah, the Blessed and Exalted, will raise up from my progeny a righteous man whose name will be like my name (or like the name of a prophet). He will fill this earth with justice, fairness and equity. In that blessed era the sky will not withhold a single drop of its rain, and the earth will not hold back anything of its produce and vegetation (rather, it will bring forth all its greenery). That man will remain among the people for seven or eight years, and if it is longer, then nine years."
Imam al-Bazzar (may Allah have mercy on him) narrated this hadith through the chain of Isma'il bin Abi al-Harith and Ahmad bin Yahya al-Susi from Dawud bin al-Muhabbar, and he also mentioned that Ma'mar narrated it through Abu Harun, from Mu'awiyah bin Qurrah, from Abu al-Siddiq, from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him).

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him): My dear friend Abu al-Qasim (peace and blessings be upon him) told me: "The Hour will not be established until a man from my household comes out against these people (as a ruler), and he will strike them (with his power and strength) until they return to the truth." Bashir bin Nahik said: I asked: "For how long will he rule?" Sayyiduna Abu Hurayrah (may Allah be pleased with him) replied: "Five and two." I asked again: "What is meant by five and two?" He said: "I do not know (whether seven years are meant or something else)."
The chain of this hadith is hasan (good); Ibn Hibban declared Isa bin Hilal al-Sadafi thiqah (trustworthy) and Imam al-Dhahabi called him salih al-hadith (fair in hadith), while al-Murajja bin Raja' al-Yashkuri is a saduq (truthful) narrator. Imam Abu Ya'la narrated it in his Musnad (6664).