Imam Ali Ar-Rida (transliterated also into Imam Ali Ar-Ridah; Imam Al-Ridah; Imam Al-Rida) is the eighthImam for Shiite Muslims. He was born on 11 Zulqi‘dah 148AH (≈29December765) in the holy city of Medina. His father is Imam Musa ben J‘afar (Imam Musa Al-Kazim) and his mother is Najma (or Najmah). His teknonymic (Kunya)is Abo Al-Hasan and his title is Ar-Rida(the one who is satisfied).
Imam Ali Ar-Rida was born during the reign of Abbasids. After the death of his father, Imam Ar-Rida became the successor Imam and resided in Medina to complete the missions of his fathers’ Imams through delivering the divine teachings to the Muslim community. When the then Abbasid Caliph Al-Ma’mon obtained the power after defeating his brother and then resided in Greater Khorasan (or Khurasan) after taking the city of Merv the capital of his caliphate (Merv currently locates in Turkmenistan), he summoned Imam Ar-Rida from Medina and appointed him as his Crown Prince on 7 Ramadan 201 AH (≈29March 817).This declaration has been described as a political step to assuage Imam Ar-Rida’s followers in Khorasan and to entice them to be loyal to his government.
In his new hometown, Imam Ar-Rida completed the mission of propagating knowledge, morale and wisdom to the society.
Imam Ar-Rida passed away on 17 Safar 203 AH (≈24August 818)and was buried in the city of Mashhad, Iran (Mashhad was known at that time by Tus), where a shrine has been built. It is believed that Imam Ar-Rida was assassinated by poison.