Muhammad ibn Ali al-Hadi was the son of Ali al-Hadi

Ali al-Hadi

‘Alī al-Hādī , also known as ‘Alī an-Naqī was the tenth of the Twelve Imams. His full name is ‘Alī ibn Muhammad ibn ‘Alī. The exact date of his birth and death are unknown, but it is generally accepted that he was born between 827–830 CE and he died in 868 CE.- Early years :‘Alī al-Hādī was born...

 and the brother of Hasan al-Askari

Hasan al-Askari

Hasan al-‘Askarī was the eleventh of the Twelve Imams. His given name was Hasan ibn ‘Alī ibn Muhammad...

, the 10th and 11th Twelver Shia Imams respectively.

A section of the Imamate Shiites believed that the Awaited Imam Mahdi

Mahdi

In Islamic eschatology, the Mahdi is the prophesied redeemer of Islam who will stay on Earth for seven, nine or nineteen years- before the Day of Judgment and, alongside Jesus, will rid the world of wrongdoing, injustice and tyranny.In Shia Islam, the belief in the Mahdi is a "central religious...

 was Muhammad ibn Ali al-Hadi, who died suddenly in Dajil. They believed in his occultation

The Occultation

The Occultation in Shia Islam refers to a belief that the messianic figure, or Mahdi, who in Shi'i thought is an infallible male descendant of the founder of Islam, Muhammad, was born but disappeared, and will one day return and fill the world with justice. Some Shi'is, such as the Zaidi and...

, like that claimed for Isma'il ibn Jafar, and they did not believe in his death. This sect was known as the Muhammadite Shia

Muhammadite Shia

The Muhammadite Shia were a Shia sect who believed that due to the supposed lack of a son for Hasan al-Askari, they had to rethink the legitimacy of his Imamate. Therefore, they instead believed in the Imamate of his brother Muhammad ibn Ali al-Hadi, who died 7 years before the death of his father...

.