All the Twelve Imams who were the true successors of the Prophet were born Imams, they did not become Imams. They did not attend any school or centre of learning. Their knowledge was directly from Allah. However, there was certain training and information that an Imam got from his father and grandfather who themselves were Imams. In this manner Imam Zainul Abidin’s life was influenced by three Imams: Imam Ali (A.S), Imam Hasan (A.S) and Imam Husain (A.S).
So far as his father was alive, Imam Zainul Abidin (A.S) spent significant part of his life in prayers and in service of human beings. He was the champion of the poor and the sick.
When his father, Imam Husain (A.S) left Medina for Iraq in A.H. 60, Imam Zainul Abidin went together with him. Because the world cannot survive even .for one atom of a second without the presence a “Masoom” Imam, Imam Zainul Abidin (A.S) could not join his farther and other male members of his caravan in becoming martyrs of Islam on the day of Ashura. Allah made a special for that. Imam Zainul Abidin (A.s) was very on the day of Ashura and he could not take part in the Jihad.
Even then, when his father, Imam Husain (A.S) came to visit him, Imam Zainul Abidin (A.S) requested his father to allow him, too, to give his life fighting in the way of Allah. Imam Husain (A.S) told him that for Islam he had a more difficult “Jihad” to fight than the one he was wishing to do at that time, namely taking responSibility of the womenfolk from the family of the Prophet and staying with them to Kufa, and then to Damascus and then return with them to Medina.
Truly speaking, for him, it would have been very easy to die on the battle field as a martyr than to be taken as prisoner of war and see all the insult and humiliations thrown on him and on the womenfolk of the house of the Prophet. However, he did what Allah wished him to do.
After the martyrdom of Imam Husain (A.S), the survival of Islam depended on Imam Zainul Abidin (A.S), and that also at a tender age of twenty two. He had a very hard job of letting the world know the mission of Imam Husain (A.S.) and exposing the evil intentions of Yezid and the Bani Umayyah. He had to keep the message of Islam alive and save it from being confused by the evil Bani Umayyah.
Source:
A Brief Biography of Ali Ibn Husain (a.s)
By Muhammad Reza Dungersi. PH.D.
[Vol. 4, p. 7-8].