Ibn Hibban

Sayyiduna Safinah (may Allah be pleased with him) narrates this statement of the Noble Prophet (peace and blessings be upon him): "The Caliphate will last for thirty years, after that there will be kings. The caliphs and kings will be twelve."
(Imam Ibn Hibban, may Allah have mercy on him, says:) This is the narration that has caused confusion for the one who does not have expertise in the science of hadith, and he says that its last part contradicts its first part, because the Noble Prophet (peace and blessings be upon him) stated that the caliphate will last for thirty years, then he said: after that, all will be kings. So, after thirty years, whoever becomes the caretaker of the affairs of the Muslims, all those people will be considered kings. Then the Noble Prophet (peace and blessings be upon him) said: the number of caliphs and kings will be twelve. So the Noble Prophet (peace and blessings be upon him) limited the number of caliphs and kings to only twelve.
Therefore, apparently, it seems that these words are contrary to the initial part.
However, by the grace and mercy of Allah Almighty, this is not the case, and it is not necessary that if a person is deprived of the ability to reach a correct proof, he should start declaring the transmitted narrations as incorrect. Rather, it is necessary that he should acquire knowledge from its original sources and gain understanding about the Sunnah, so that he may know that the one who is infallible and does not speak from his own desire, but only speaks what is revealed to him, there is no contradiction or difference in his statements. According to us, the meaning of this narration is that after thirty years, the rulers who will come can be called caliphs out of necessity (i.e., in a state of compulsion), even though in reality they will be kings, and the last of these twelve caliphs is Umar ibn Abdul Aziz. When the Noble Prophet (peace and blessings be upon him) mentioned that the true caliphate will last for thirty years, and then after that, the last of the twelve caliphs is Umar ibn Abdul Aziz, then he will be counted among the rightly guided caliphs. So, those who came between him and the first four caliphs, the word caliphs has been used for them. The situation is as follows: when Allah Almighty took the blessed soul of the Noble Prophet (peace and blessings be upon him) and transferred him to Paradise, this was on Monday night, the night of 12th Rabi' al-Awwal, 11 AH. After that, on the second day after the passing of the Noble Prophet (peace and blessings be upon him), that is, on Tuesday, Sayyiduna Abu Bakr (may Allah be pleased with him) was chosen as caliph. Then Sayyiduna Abu Bakr (may Allah be pleased with him) passed away on the night of 17th Jumada al-Thani. His caliphate lasted two years, three months, and twenty-two days. After that, the next day, that is, the day after the passing of Sayyiduna Abu Bakr (may Allah be pleased with him), Sayyiduna Umar ibn Khattab (may Allah be pleased with him) was chosen as caliph. Then Sayyiduna Umar (may Allah be pleased with him) was martyred. His caliphate lasted ten years, six months, and four days. Then Sayyiduna Uthman Ghani (may Allah be pleased with him) became caliph. Sayyiduna Uthman (may Allah be pleased with him) was martyred, so his caliphate lasted twelve years, less twelve days. Then Sayyiduna Ali ibn Abi Talib (may Allah be pleased with him) was made caliph; he was martyred. His caliphate lasted five years and three months, less fourteen days. When Sayyiduna Ali ibn Abi Talib (may Allah be pleased with him) was martyred, it was the 17th of Ramadan, 40 AH. After that, the people of Kufa pledged allegiance to Sayyiduna Imam Hasan (may Allah be pleased with him), and the people of Sham pledged allegiance to Sayyiduna Muawiyah ibn Abu Sufyan (may Allah be pleased with him) in Aaliya. Then Sayyiduna Muawiyah set out towards Kufa (for battle), and Sayyiduna Imam Hasan ibn Ali (may Allah be pleased with them both) set out towards him. Near Anbar, both met, and they made peace under an agreement with certain conditions. So Sayyiduna Imam Hasan (may Allah be pleased with him) handed over the matter of government to Sayyiduna Amir Muawiyah. This was on Monday, 25th Rabi' al-Awwal, 41 AH. This year was called the year of unity.
Then Sayyiduna Muawiyah (may Allah be pleased with him) passed away in Damascus; this was on Monday, 22nd Rajab al-Murajjab, 60 AH. His rule lasted 19 years and a little less than four months. When he passed away, he was 78 years old.
After that, his son Yazid ibn Muawiyah became his successor on Monday, the same day his father passed away.
He died in Hawarin, which is a village of Damascus; this was on 14th Rabi' al-Awwal, 64 AH. At that time, he was 38 years old, and his rule lasted three years, eight months, and a few days less.
Then his son Muawiyah ibn Yazid was pledged allegiance to on 15th Rabi' al-Awwal, 64 AH. He died on 25th Rabi' al-Thani, 64 AH. His rule lasted 40 days. When he died, he was 21 years old.
Then the people of Sham pledged allegiance to Marwan ibn Hakam, and the people of Hijaz pledged allegiance to Abdullah ibn Zubair. Then, on Wednesday, 3rd Dhu al-Qi'dah, 64 AH, Marwan became the complete ruler. Marwan ibn Hakam died in the month of Ramadan in Damascus in 65 AH. At that time, he was 63 years old, and his rule lasted a little less than ten months. Then the people of Sham pledged allegiance to Abdul Malik ibn Marwan, on the same day his father died. Abdul Malik died in Damascus in Shawwal, 86 AH. At that time, he was 62 years old. Then the people of Sham pledged allegiance to his son Walid, on the same day Abdul Malik died.
Then Walid died in Damascus on 15th Jumada al-Thani, 96 AH. On the day he died, he was 48 years old, and his rule lasted nine years and eight months. Then allegiance was pledged to Sulayman ibn Abdul Malik, who was his real brother. Sulayman died at the place of Dabiq on Friday, 10th Safar, 99 AH. At that time, he was 45 years old, and his rule lasted two years, eight months, and five days. Then the people pledged allegiance to Umar ibn Abdul Aziz on the same day Sulayman died. Umar ibn Abdul Aziz died in the land of Homs at the place of "Dayr Sim'an" on Friday, 5th Rajab al-Murajjab, 101 AH. On the day he died, he was 41 years old, and his caliphate lasted two years, five months, and five days. He was the last of those twelve caliphs about whom the Noble Prophet (peace and blessings be upon him) informed his Ummah.