al-Ma'mun's designation of Ali al-Rida as heir

In 201 AH al-Ma'mun removed his brother al-Mu'tamin from the succession and made Ali al-Rida ibn Musa al-Kazim heir apparent. ¹

al-Suyuti says that al-Ma'mun wrote about this to all regions, gave Ali the title al-Rida, struck dirhams in his name, and married him to his daughter. He ordered that black be abandoned and green worn. ¹

al-Suyuti attributes this to al-Ma'mun's excessive Shi'ism, to the point that it is said he intended to depose himself and hand over the affair to Ali. This is al-Suyuti's explanation, not the museum's verdict. ¹

al-Suyuti says that this weighed very heavily on the Banu al-Abbas. They went out and gave their allegiance to Ibrahim ibn al-Mahdi, known as al-Mubarak. ¹

This is al-Suyuti's account alone. What is not set out here is the view of academic studies and of other sources. The date is derived and needs an additional source.