Political Condition

The period of his Imamate coincided with the most revolutionary and eventful era of Islamic history which saw the downfall of the Umayyad Empire and the rise of the 'Abbasid caliphate. The internal wars and political upheavals were bringing about speedy reshufflements in government. Thus, the Holy Imam witnessed the reigns of various kings starting from 'Abdu 'l-Malik down to the Umayyad ruler Marwan al-Himar. He further survived till the time of Abu 'l-'Abbas as-Saffah and al-Mansur among the 'Abbasids. It was due to the political strife between two groups viz., the Umayyads and 'Abbasids for power that Imam was left alone undisturbed to carry out his devotional duties and peacefully carry on his mission to propagate Islam and spreading the teachings of the Holy Prophet. In the last days of the Umayyad rule, their Empire was tottering and was on the verge of collapse, and a most chaotic and demoralized state of affairs prevailed throughout the Islamic State. The 'Abbasids exploited such an opportunity and availing themselves of this political instability, assumed the title of "Avengers of Banu Hashim". They pretended to have stood for the cause of taking revenge on the Umayyads for shedding the innocent blood of the Holy Imam Husayn. The common people who were groaning under the yoke of the Umayyads were fed up with their atrocities and were secretly yearning for the progeny of the Holy Prophet to take power. They realized that if the leadership went to the Ahlul-Bayt, who were its legitimate heir, the prestige of Islam would be enhanced and the Prophet's mission would be genuinely propagated. However, a group of the 'Abbasids secretly dedicated their lives to a campaign for seizing power from the hands of the Umayyads on the pretext that they were seizing it only to surrender it to the Banu Hashim. Actually, they were plotting for their own ends. The common people were thus deceived into supporting them and when these 'Abbasids did succeed in snatching the power from the Umayyads, they tuned against the Ahlu 'l-Bayt. 

Religious Condition
The downfall of the Umayyads and the rise of the 'Abbasids constituted the two principal plots in the drama of Islamic history. This was a most chaotic and revolutionary period when the religious morals of Islam had gone down and the teachings of the Holy Prophet were being neglected, and a state of anarchy was rampant. It was amidst such deadly gloom that the virtuous personage of Imam Ja'far as-Sadiq stood like a beacon of light shedding its lustre to illuminate the ocean of sinful darkness around. The world got inclined towards his virtuous and admirable personality. Abu Salamah al-Khallal also offered him the throne of the caliphate. But the Imam keeping up the characteristic tradition of his ancestors flatly declined to accept it, and preferred to content himself with his devotional pursuits and service to Islam. On account of his many debates with the priests of rival orders like Atheists, Christians, Jews, etc.

Teachings

The versatile genius of Imam Ja'far as.-Sadiq in all branches of knowledge was acclaimed throughout the Islamic world, which attracted students from far-off places towards him till the strength of his disciples had reached four thousand. The scholars and experts in Divine Law have quoted many ahadith (traditions) from Imam Ja'far as.-Sadiq. His disciples compiled hundred of books on various branches of science and arts. Other than fiqh (Islamic jurisprudence), hadith (tradition), tafslr (exegesis of the Holy Qur'an), etc., the Holy Imam also imparted mathematics and chemistry to some of his disciples. Jabir ibn Hayyan at.-Tusi, a famous scholar of mathematics, was one of the Imam's disciples who benefited from the Imam's knowledge and guidance and was able to write four hundred books on different subjects.

It is an undeniable historical truth that all the great scholars of Islam were indebted for their learning to the very presence of the Ahlu 'I-Bayt who were the fountain of knowledge and learning for all. Allamah ash-shibli writes in his book Siratu'n- Nu'man: "Abu Hanifah remained for a considerable period in the attendance of Imam Ja'far as-Sadiq, acquiring from him a great deal of precious research on fiqh and hadith. Both the sects - Shi'ah and Sunni - believe that the source of Abu Hanifah's knowledge was mostly derived from his association with Imam Ja'far as-Sadiq." The Imam devoted his whole life to the cause of religious preaching and propagation of the teachings of the Holy Prophet and never strove for power. Because of his great knowledge and fine teaching, the people gathered around him, giving devotion and respect that was his due. This excited the envy of the 'Abbasid ruler al-Mansur ad-Dawaniqi who fearing the popularity of the Imam, decided to do away with him. 

Allamah Tabatabai writes

Imam Ja'far ibn Muhammad, the son of the Fifth Imam, was born in 83/702. He died in 148/765 according to Shi'ite tradition, poisoned and martyred through the intrigue of the 'Abbasid caliph al-Mansur. After the death of his father he became Imam by Divine Command and decree of those who came before him. During the Imamate of the Sixth Imam greater possibilities and a more favourable climate existed for him to propagate religious teachings. This came about as a result of revolts in Islamic lands, especially the uprising of the Muswaddah to overthrow the Umayyad caliphate, and the bloody wars which finally led to the fall and extinction of the Umayyads. The greater opportunities for Shi'ite teachings were also a result of the favourable ground the Fifth Imam had prepared during the twenty years of his Imamate through the propagation of the true teachings of Islam and the sciences of the Household of the Prophet.

The Imam took advantage of the occasion to propagate the religious sciences until the very end of his Imamate, which was contemporary with the end of the Umayyad and beginning of the 'Abbasid caliphates. He instructed many scholars in different fields of the intellectual and transmitted sciences, such as Zurarah ibn A'yan, Muhammad ibn Muslim, Mu'minu 't.-Taq, Hisham ibn al-Hakam, Aban ibn Taghlib, Hisham ibn Salim, Hurayz, Hisham al- Kalbi an-Nassabah and Jabir ibn Hayyan (the alchemist). Even some important Sunni scholars such as Sufyan ath-Thawri, Abu Hanifah, the founder of the Hanafi school of law, al-Qadi as-Sukuni, al-Qadi Abu 'I-Bakhtari, and others, had the honour of being his students. It is said that his classes and sessions of instructions produced four thousand scholars of hadith and other sciences. 

The number of traditions preserved from the Fifth and Sixth Imams is more than all the hadith that have been recorded from the Prophet and the other ten Imams combined. But toward the end of his life the Imam was subjected to severe restrictions placed upon him by the 'Abbasid caliph al-Mansur, who ordered such torture and merciless killing of many of the descendants of the Prophet who were Shi`te that his actions even surpassed the cruelty and heedlessness of the Umayyads. At his order they were arrested in groups, some thrown into deep and dark prisons and tortured until they died, while others were be- headed or buried alive or placed at the base of or between walls of buildings, and walls were constructed over them. Hisham, the Umayyad caliph, had ordered the Sixth Imam to be arrested and brought to Damascus.

Later, the Imam was arrested by as-Saffah, the 'Abbasid caliph, and brought to Iraq. Finally, al-Mansur had him arrested again and brought to Samarrah where he had the Imam kept under supervision, was in every way harsh and discourteous to him, and several times thought of killing him. Eventually the Imam was allowed to return to Medina where he spent the rest of his life in hiding, until he was poisoned and martyred through the intrigue of al-Mansur. Upon hearing the news of the Imam's martyrdom, al-Mansur wrote to the governor of Medina instructing him to go to the house of the Imam on the pretext of expressing his condolences to the family, to ask for the Imam's will and testament and read it. Whoever was chosen by the Imam as his inheritor and successor should be beheaded on the spot. Of course, the aim of al-Mansur was to put an end to the whole question of the Imamate and to Shi`ite aspirations. When the governor of Medina, following orders, read the last will and testament, he saw that the Imam had chosen four people rather than one to administer his last will and testament: the caliph him- self, the governor of Medina, 'Abdullah Aftah, the Imam's older son, and Musa, his younger son. In this way the plot of al-Mansur failed. (Shi'ite Islam) 

Death

On 25th Shawwal 148 AH, the governor of Medina by the order of al-Mansur, got the Imam martyred through poison. The funeral prayer was conducted by his son Imam Musa al-Kazim, the Seventh Imam, and his body was laid to rest in the cemetery of Jannatu'l-Baqi'. 

Al-Imam as-Sadiq, peace be Upon him, said: 

One who has these five characteristics is the choicest of men: one who feels joyous when he does something good; one who repents when he does something bad; one who is grateful when he receives something from Allah; one who patiently endures Allah's trials; one who forgives when he is done some injustice or wrong. 

closer to Allah: forgiving one who has wronged him; being generous to one who had deprived him; being kind to a kinsman who has not observed his rights of kinship. 

The true believer does not transgress the limits of fairness in a fit of anger; he does not do anything unjutifiable for the sake of favour to some; neither does he take more than his due share, though he may have the power. 

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