Imam al-Hussein (a.s) was a man of faith and action. During nights, he worshipped Allah in privacy while during the day he worked hard and guided the people. He was constantly mindful of the poor and the needy, and he used to visit them and cheer them up.
Al-Imam al-Hussein (a.s) always helped the poor as much as he could. at night he would carry sacks of food to the houses of the poor and leave them near the doors. He worked hard to eradicate poverty, establish justice and acquaint the people with Allah.
During the time of al-Imam al-Husayn a tyrant called Yazid became the ruler. Yazid called himself the successor of Muhammad (s.a.w) but this was a lie. He used to spend the income of the Islamic realm on drinking, gambling and wild parties. Public wealth was wasted for supporting his regime and the rights of the poor were trampled upon. In this way he totally scorned the instructions of Islam.
When Yazid became ruler of the Muslims he immediately demanded al-Imam al-Hussein (a.s) to recognize him as the ruler and accept his leadership; but al-Imam al-Hussein (a.s) was the true successor of Prophet Muhammad (s.a.w) and could not accept and endorse the leadership of an oppressor. He began to enlighten and awaken the people about Yazid and exhorted them to dissociate from him. He would tell them:
"Do you not see that the truth is being trampled upon and the falsehood and oppression are prevailing? In such conditions, a muslim must be ready for martyrdom in defense of the right. Martyrdom and self-sacrifice for the sake of truth is victory and success, while life with the oppressors is no more than shame and disgrace."
At that time the people of kufa (Iraq) were loving followers of al-Imam Ali (a.s)
who had been suffering at the hands of Yazid and his father Mu"awiyah. They invited al-Imam al-Hussein (a.s) to Kufa to lead them against Yazid and his wicked rule. Al-Imam al-Hussein (a.s) had indeed decided to rise up and fight, and so he accepted the invitation and set off for kufa.
When the Imam (a.s) and his followers were near Kufa, they were met by Yazid"s troops. The troops wanted to arrest al-Imam al-Hussein (a.s) and his followers and take them to Yazid. The Imam (a.s) told them:
"Never will I accept disgrace and surrender to Yazid, Death for me is superior to disgrace and I am ready to defend Islam and the Muslims until I am Martyred."
At a place called Karbala al-Imam al-Hussein (a.s), his family and helpers were surrounded by Yazid"s troops. The Imam (a.s) and his followers stood firm as they fought against the thousands of troops of Yazid. Finally, on 10th Muharram, 61 AH (the day we call Ashura) they were martyred
Al-Imam al-Hussein (a.s) and his followers were martyred, but they did not submit to injustice and oppression. They defended Islam and the Muslims.
For this reason we call al-Imam al-Hussein (a.s) "Sayyid al-Shuhada" which means lord of the martyrs. Now the turn has come for us to safeguard and defend Islam. We must shoulder this magnificent responsibility.
source : tebyan