What is the authenticity and explanation of the hadith of Nu'man ibn Bashir in Imam Ahmad's Musnad regarding the division of time into Prophethood, then a Rightly-Guided Caliphate, then an oppressive kingship, then a tyrannical kingship, then the return of the Rightly-Guided Caliphate? Has it been fully realized, or are we in one of its eras? And what is the meaning of "oppressive" and "tyrannical"? And what is the significance of his saying "then he became silent"?

Imam Ahmad narrated from Nu’man ibn Bashir a prophetic hadith describing the succession of ruling patterns after prophethood: “There will be prophethood, then a caliphate on the prophetic methodology, then a biting kingship, then an oppressive kingship, then a caliphate on the prophetic methodology.” Al-Albani graded this hadith as authentic.

Imam Ahmad also narrated from Safina that the caliphate in his Ummah would last for thirty years (the caliphate of Abu Bakr, Umar, Uthman, and Ali), and then there would be kingship after that.

The caliphate on the prophetic methodology refers to the caliphate of Abu Bakr, Umar, Uthman, and Ali. The biting kingship is an unjust and tyrannical rule, and the oppressive kingship is a rule by force.

Scholars have differed on determining the realization of these stages. Some believe that the caliphate of Umar ibn Abd al-Aziz was the second caliphate on the prophetic methodology, while Al-Albani considers this unlikely because Umar ibn Abd al-Aziz’s caliphate was close to the Rightly Guided Caliphate and was not preceded by two kingships (biting and oppressive). He suggests that we are currently in the era of oppressive kingship, and the second caliphate on the prophetic methodology will be with the advent of the Mahdi.

As for the phrase "then he fell silent" in the hadith, it indicates the conclusion and completeness of the hadith.