Born in Madina 11th Zeeqaad 148 Hijri (1.1.766 AD). Died in the city of Tus Iran on 17th Safar 203 Hijri (26.5.819 AH) Period of Imamate 20 years.
His grandfather Imam Ja’far Al-sadiq (as) died one month before the birth of Imam Ridha’ (as) The family must have been consoled by his birth which took place after such a great loss. He was brought up and instructed by his affectionate father under whose supervision he passed his boyhood and youth. He availed himself of the instructions of his learned father for thirty one years, till the later was taken to Baghdad to suffer the hardship of imprisonment for four years till his death.
Imam Musa Ibn Ja’far (as) could foresee that the hostile Abbasid ruler would not allow him to live peacefully and circumstances would take such a turn that his followers would not be able to see him or enquire about his successor prior to his death.
So while free and undisturbed in Madinah he felt the need to introduce his successor to his followers. He, therefore, assembled seventeen prominent dignitaries from the descendants of Imam ‘Ali (as) and proclaimed that his son ‘Ali Ibn Musa (as) would succeed him.
He also wrote his will on which 60 respected elders of Madinah signed as witnesses. Such elaborated arrangements were never made by any other Imam and they proved to be most appropriate due to the controversy about the Imamate which ensued after the death of Imam Musa Ibn Ja’far (as) .
Imam Ridha’ (as) was 35 years old when his father died in prison of Harun al-Rashid in Baghdad and the responsibilities of the Imamate devolved on him. At that time Harun Al-Rashid was the absolute ruler of Baghdad and the descendants of Imam ‘Ali (as) were passing as ever, through trials and tribulations because of the tyranny of the Abbasid ruler.
Yet Imam Ridha’ (as) carried on the responsibility of administering the Divine Law of Shari’ah as taught by the Holy Prophet and Imams of the Ahlul Bayt after him.
After putting an end to the life of Imam Musa Ibn Jaa’far (as) Harun al-Rashid lived for ten years. He had less tolerance for the existence of Imam ‘Ali Ridha’ (as) , then he did for his revered father. But he also knew that his Government had already lost face due to its prolonged maltreatment and eventual assassination of Imam Musa Ibn Ja’far (as) or perhaps the tyrant felt the stings of conscience which kept him from harassing the 8th Imam.
It is said that once Yahya Barmaki, his Prime Minister, in order to gain the ruler’s favor, informed Harun that Imam ‘Ali Ibn Musa (as) claimed Imamate in the same way his father had done, Harun coldly replied, “We have already inflicted cruelties on his father, do you expect me to annihilate this family altogether.
Still, Harun was antagonistic towards the Prophet’s descendants and persisted in maltreatment of most of them in Madina. The local Governors of Madina who wished to please the ruler could not afford to be fair to Ahlul Bayt. People could not visit the Imam freely seek his knowledge, and he had little chance to teach his followers openly, for the eyes of the agents of Caliph focused unceasingly on the activities of the Imam.
Political wranglings in Baghdad between the two sons of Harun were rocking the Empire. His elder son Amin who had an Arab mother had the support of the Arabs and most of the Abbasid elders, while the younger son Mamun had a Persian mother and was supported by the Persians.
To console both factions Harun took a pledge from both his sons that after his death Amin will rule the Arab part of the Empire while Mamun will rule the Persian side.
When Harun died in faraway Tus, the most northern town of his Persian Empire, Mamun was with him and buried him there. Amin in Baghdad immediately proclaimed himself the Caliph of the whole empire and immediately deposed Mamun from the rulership of the Persian Province. Mamun’s main concern was to subdue the Persian province under any circumstances.
He realized that the majority of Persians favored the teachings of Ahlul Bayt and if somehow he could persuade the Imam of the Ahlul Bayt in Madina to side with him, he could confirm his rule there. Once he felt secure on that side of the Empire, he would then rise against his brother and easily depose him.
So the orders were sent out for the Imam to leave his home in Madina and go to the Abbasid ruler in faraway Tus. Imam, as if by some miracle knew what was to come. So he left his wife and only son Muhammad Ibn ‘Ali al Jawad, later known as Imam Muhammad Taqi (as) in Madina.
He also called many elders of Madina mostly from Banu Hashim and told them of his call to go to the outpost of the Empire to see Mamun. The date of his departure was in the month of Rajab 200 Hijri. It was a long journey to Merve and the Imam set out on this momentous journey with some of his friends who were loyal to him throughout his life.
His journey began from Madina to Makka where he performed the Umra, then he took almost the same route as Imam Husayn (as) took in 61 hijri towards Karbala’. Half way through the hills of Hejaz when he crossed over to the desert of Najd his route changed to that of Imam Husayn (as) and his caravan moved towards the eastern side and reached the town of Basra in the month of Shawwal.