Imam Reza (A.S.) grew up under the auspices of his father at a time when the abbasid usurpers, Mansur, Mahdi, Hadi and Harun ruled the Islamic state in succession.In the year 179 AH (795 AD) , Due to Imam Musa al-Kazem's (A.S.) unending struggle ahainst the cruel ruler, Imam Reza (A.S.) saw his noble father arrested and taken to Iraq on the order of Harun.

Four years later on 25th Rajab 183 AH (799 AD), the seventh Imam was poisoned and martyred by Sindi bin Shahik at Baghdad on the instructions of the cruel caliph, and was laid to rest in graveryard of the Quraysh , which eventually became a venerate pilgrim site called kazemain. The mantle of Imamate , the divinely-designated leadership of mankind, thus fell on shoulders of Imam Reza (A.S.), when he was 35 years of age.

For the next ten years Imam Reza (A.S.) expounded the sciences of Islam and guided his followers in Medina.