Abu Muhammad ‘Ali ibn Husayn, known as Zaynu’l-Abidin (ornament of the worshippers) and also by the titles as-Sajjad (the prostrator) and az-Zaki (the pure), is regarded as the Fourth Imam by Twelver Shi’is. He had been born in the year 38/658 in Medina. His father was the Third Imam, Husayn, and, according to Shi’i tradition, his mother was Shahrbanu, the daughter of Yazdigird, the last Sassanian king of Iran.

In previous section it has already been related that ‘Ali was the only son of Husayn to survive the slaughter of Karbala because ha had been too eak and sick to fight. It ahs also been ralated that he was sent acaptive to Damascus and then freed by Yazid and allowed to retire to Medina.

Husayn’s martyrdom in 61/680 had a profound effect on the Shi’a. In Kufa, towards the end of the same year, a group of Shi’a began to meet in order to discuss what they could do to atone for their failure to come to Husayn’s assisstance. They elected as their leader Sulayman ibn Surad to whom they gave the title Shaykhu’sh-Shi’a (the leader of the Shi’a). Their movement, which became known as the Tawwabun (the penitents) remained underground for four years. Then in 65/684 the Tawwabun came into the open and 3,000 of them marched against an Umayyad army of 30,000 and were killed.

In 64/683, shortly before the Tawwabun uprising, Yazid the Umayyad Caliph died. There followed the brief six-month reign of his sickly son and then Umayyads fell into disarray with factional fighting. This created a chance for all those factions that had been opposed to the Umayyads. In Kufa, the leaders of the different tribal factions met and decided to invite ‘Abdu’llah ibn Zubayr, who had already in 61/680 proclaimed his Caliphate in the Hijaz, to send his representative to govern the city. Thus Iraq came under the rule of Ibn Zubayr. However, there also arrived n Kufa, atthis time Mukhtar ath-Thaqafi who was advancing a propaganda among the Shi’is in favour of Muhammad ibn al-Hanafiyya, the Imam ‘Ali’s third son by a women of the tribe of Hanifa (i.e. not by Fatima, the daughter of the Prophet). The Tawwabun who were about to set off on the road to martyrdom refused to ally themselves with Mukhtar, but after their defeat Mukhtar’s cause grew as there was no alternative leadership among the Shi’a of Kufa. Eventually, in 66/686, Mukhtar was strong enough to seize possession of Kufa.

Whereas the Tawwabun and indeed Shi’ism itself had been primarily an Arab movement up to this time, Mukhtar was the first to mobilise for the Shi’i cause the large numbers of Iranians who, in the social structure of the Islamic Empire, held an inferior status as Mawali (clients of the Arab tribes). Mukhtar in his propaganda emphasised the role of Ibn al-Hanafiyya as the Mahdi (the rightly-guided one) who would deliver the Muslims from oppression and restore justice. Mukhtar uprising was put down in 67/686 or 68/687 and Mukhtar himself killed, but the propaganda on behalf of Ibn al-Hanafiyya continued, and when the latter died in 81/700 a group of his followers considered that he had not died at all but had gone into occultation and would return. Mukhtar and the supporters if Ibn al-Hanafiyya were thus the first to bring into prominence two keys ideas that were henceforth to be of great importance in the development of Shi’i thought; the idea of Mahdi and the concept of occultation and return.

During these turbulent years, the Fourth Imam Zaynu’l-Abidin kept very much in the background, not involving himself in the politics and upheavals of the period. So completely did he set himself apart from an active role that neither ‘Abdu’llah ibn Zubayr nor later al-Hajjaj, when he defeated ‘Abdu’llah, felt it necessary to place any restriction on Zaynu’l-’Abidins movements nor to extract from him any pledge of obedience.

From what is recorded of Zaynu’l-’Abidin’s life, it would appear that he led a very secluded pious life with only a handful of close associates. It is recorded that he spent a great deal of time weeping over the martyrs of Karbala. His name as-Sajjd (the prostrator) bore witness to the numerous times that he prostrated himself before God and it is said that the resulting calluses on his forehead needed to be shaved down twice a year.

Although he kept himself apart from the people and although much of the support of the Shi’is was diverted to Muhammad ibn al-Hanafiyya, there is no doubt that Zaynu’l-Abidin was held in great respects by all. Several leading jurists of the time, such as az-Zuhri and Sa’id ibn al-Musayyib, were counted among his close associates. As for followers and disciples, it is difficult to be sure of their number. It seems fairly certain that there were hardly any until the collapse of Mukhtar’s revolt and the end of Ibn Zubayr’s Caliphate in 73/692. There is, however, the famous story told that when Hisham, the son of the Caliph ‘Abdu’l-Malik came on pilgrimage to Mecca, he found that because of the crowds, he was unable to approach with ease. When he asked who it was for whom the crowd parted so respectfully while he, the son of the Caliph, was ignored. he was told it was Zaynu’l-’Abidin. It is also reported that the Caliph ‘Abdu’l-Malik brought Zaynu’l-’Abidin to Damascus and held him in prison briefly.