Born in Madina on 7th Safar 128 Hijri (10.11.745AD). Died in Baghdad Iraq 25th Rajab 183 Hijri (4.9.799 AD) Period of Imamate was 35 years.
Imam Musa Ibn Ja’far was born during the struggle between the Ummayads and the Abbasids. He was only four years old when Abul Abbas “Saffah”, “The Shedder of Blood”, came to the throne as the first Abbasid caliph. For twenty years he was under the authority of his father, who died ten years before the end of the long reign of Mansur.
The Imamate of the 7th Imam extended through the ten remaining years of the caliphate of Mansur, and included the ten years of the rule of Mahdi, one year and some months of Hadi and about twelve years of the reign of Harun al- Rashid. Thus for thirty five years he was the Imam. He held this coveted distinction as the longest period of Imamate of the Eleven Imams.
With six brothers and nine sisters Imam Musa (as) grew up in a large family. Ismail the oldest brother died at a young age and Musa was chosen by Divine providence to succeed his father as the Imam. There were those among the followers of the 6th Imam who thought that Imamate should be hereditary and therefore the eldest son of the 6th Imam should succeed.
They misunderstood the whole concept of Imamate which was neither hereditary nor mandatory for any one person. It was divinely selected and the Imam at his death bed reveals the name of the next Imam.
The Abbasid caliphs were always on the alert with this distinctive source of Imamate and our 7th Imam was fully aware of this danger. The Caliphs were on the alert to discover any real or imaginary disloyalty with the Imam or his followers and they would immediately put them under arrest.
This natural anxiety, however, does not appear to have seriously interrupted his life as an Imam. He continued to disseminate Qura’nic teachings as his father Imam Ja’far al-Sadiq (as) used to do through the Islamic schools opened in Madina during the life of the 5th Imam.
Ibn Khalikan related that caliph Mansur saw in his dream Imam ‘Ali (as) who was reciting the verse from the Qur’an, “O’Muhammad, were you ready therefore, if you had been put in authority, to commit evil on the earth and to violate the ties of blood.” Mansur sent for his favorite companion Ibn Younus at night and told him of his dream.
He then said,” bring me Musa Ibn Ja’far.” The Imam Musa ibn Ja’far was brought in all the way from Madina to Baghdad. When he arrived Mansur embraced him and said to him, “Abul Hasan, I have just seen in a dream ‘Ali Ibn Abi Talib (as) who was reciting this verse.
Give me your assurance that you will not revolt against me or against any of my children. Imam replied, By Allah I have no such intentions. The caliph then gave him a thousand dinars and restored him to his family in Madina.
This story give us some idea how these Abbasid caliphs were so afraid of the Imams of Ahlul Bayt that in spite of their total lack of evidence for any kind of revolt against their earthly power, they would not leave them alone.
From time to time the Imams were brought in from Madina, kept in Baghdad either on house arrest or inside prisons under the most difficult of conditions. But it was the Imams great Divine Characters that managed to keep them going in the most severe of conditions. It is because of these uncertain times that the Imam said,
“How base is the world for a people, unless God give them joy; and how great is this life , if God is not angry with them.” Total submission to the Will of God in all circumstances.
It was widely known that Imam Musa Ibn Ja’far had been given powers of healing. Once he was passing by a house and heard little children weeping. He enquired as to why they were crying. He was told that they were orphans and their mother had just died and now they had no one to look after them.
He went inside the house, made two prostrations and prayed to God for her life. Moments later the woman stood up well and in good health. People who saw this and cried out, “Behold it is Jesus son of Mary.”
Once Harun al Rashid was visiting Madina. He went to the mosque of the Prophet near his grave and said, My Salaams to you O’cousin of our fathers. Imam Musa was there who saluted the grave of the Prophet with the words, My Salams to you O’our grandfather. At this Al-Rashid was disconcerted and went away angry.
This occurrence was sufficient to explain his first summons from Al Rashid to come to Baghdad. There he was kept in prison. But after nearly a year in prison Harun saw in a dream that an Abyssinian slave was rushing towards him with a javelin and telling him to release Musa Ibn Ja’far or he will slay him.