(Born in Madina, 10th Rajab 195 Hijri (12.4.811 AD). Died in Baghdad Iraq 29th Zeeqad 220 Hijiri (27.11.835, aged 25 years, Period of Imamate 17 years.)
At the time of the death of Imam ‘Ali Al-Ridha’ (as) our 9th Imam was only 9 years old. Some people from among the followers of Ahlul Bayt and others, doubted Imam’s eligibility to become Imam at this young age. Kulaini in his Kafi relates that the Mutawalli of the Holy Ka’aba questioned Imam for several days before he was satisfied and accepted him as the Imam of the Time.
It is an undeniable fact that the whole episode of the call for Imam ‘Ali Al-Ridha’ (as) to Tus, and his appointment as heir apparent to Mamun was a game played for political convenience to get the sympathies and support of the Persians to get his empire back from his step brother Amin. Once this was achieved Mamun had the Imam poisoned to get him out of his way.
But the fact is that Mamun being the most learned among all the Abbasid rulers, was aware that the family of the Prophet had a special type of knowledge which should be appreciated and be known to other people as long as power remained in Mamun’s hands and his authority remained supreme. This became apparent when he arrived in Baghdad victorious.
He began a policy of reconciliation with the Abbasid elders and also with those who had inclinations towards the Ahlul Bayt of the Prophet. He reappointed Hasan ibn Sahl as Governor of Iraq who had openly supported the cause of Ahlul Bayt. Ibn Sahl being a scholarly person, co-operated handsomely in the literary and cultural interest in the Emperor’s Court.
For in spite of the fact that there was warfare and political turmoil in all directions during the reign of Mamun, the period marks perhaps the apex of the oriental renaissance. There was freedom of speech and expression which resulted in open discussions on many issues which were taboos previously.
Most significant for the life of Imam Muhammad Taqi (as) was the fact that Mamun’s favors towards the Ahlul Bayt did not cease because of their scholarly and intellectual approach to Islam. Although after arriving in Baghdad Mamun replaced the Hashemite Green color to the black color of the Abbasids on flags and court dresses, he still encouraged the intellectuals to engage in open discussions about the concept of power and authority.
Indeed he took that action as political necessity for he did not want to alienate his Persian friends and supporters. For not only prominent friends of Ahlul Bayt were appointed to responsible positions, but particular public favor was shown to the family of the deceased Imam ‘Ali Al-Ridha’ (as).
It was during this stay of the 9th Imam nearby that Mamun had the chance of seeing him closely and gaining an insight into the intellectual abilities of this pious household.
Mamun convened many conferences during this period in which many intellectuals and scholars assembled in order to listen and learn from the Young Imam. Mamun told the Abbasid hierarchy that Imam ‘Ali Al-Ridha’’s son was no doubt a boy of tender age, but he had inherited his father’s virtues and qualities in full.