"O People! The Messenger of Allah has said: If anyone witnesses an oppressive ruler who permits that which has been forbidden by Allah, breaks the divine covenant, opposes the Prophet's Sunnah and regulations, and treats Allah’s servants through sinful acts and oppression, but does not express his opposition by actions or words towards that ruler, then Allah would have the right to place him in the status of the oppressive ruler (the hellfire). (Maqtal of Khaarazmi, vol. 1, p. 234)
A part of sermon by Imam Husain ibn Ali (A.S)
Pure worship, freedom, justice, piety, bravery, and all other humane characteristics manifested in Imam Ali (A.S) and his progeny were a result of true monotheism, absolute obedience and sincere attention to Allah (S.W.T). In deciding between options, the Holy Imams (A.S) always chose the option most preferred by Allah (S.W.T).
The best example of their pure intentions and obedience toward Allah (S.W.T) can be seen in the rise of Imam Husain (A.S) against Yazid from the Umayyad Dynasty: a religious movement and a rise against tyranny.
When Imam Husain (A.S) migrated from Medina to Mecca and from thereon decided to move to Iraq, some of the Islamic scholars became concerned. They remembered the prophecies made by the Messenger of Allah about his grandson, and thus knew that Imam Husain (A.S) was moving towards his martyrdom. Observing the situation of the society and the fear within people from the Umayyad dynasty, the scholars had no hope in this mission of Imam Husain (A.S). They remembered how the people of Kufa had betrayed Amir al-Mu’minin and his son, Imam Hassan ibn Ali (A.S) hence, the future was clear. In their certainty that Imam Husain (A.S) would be martyred great people like Ibn Abbas have said: “We didn’t doubt that Husain (A.S) was going to be killed in Karbala.”(Tarikh Tabari, vol. 4, p. 290, Tadhkiarah al-Khawas, p. 250) In another statement Farazdaq sent a warning message to Imam Husain (A.S): “Their hearts are with you but their swords are against you.”(Maqtal of Khaarazmi, chapter 8, p. 160) The above clearly indicates that although people knew the right was with Imam Husain (A.S), their fear from the Umayyad Dynasty and weak hearts prevented them from standing up for truth.
The rise of Imam Husain (A.S) was completely apart from personal, political, or tribal matters, for the Imam knew that the end of this journey is martyrdom. Imam Husain (A.S) was indeed a servant of Allah (S.W.T). He is the one who told his brother, Muhammad Ibn Hanafiyeh, in a well-known letter: “I am not leaving the city to revolt or to oppress anyone, nor to run injustice against what is right. I am rising to improve the community of my grandfather Muhammad (P.B.U.H&H.P); I want to invite people to good and forbid them from evil. I want to follow the path of my grandfather Messenger of Allah and my father Ali Ibn Abitalib (A.S)…” (Bihar al-Anwar, vol. 44, p. 329, Nafas al-Mahmoom, chapter 9, p. 38)
Hence, Husain (A.S) was not seeking political power, wealth, or the like. He was obeying Allah (S.W.T) by rejecting to pay allegiance to Yazid. He was submissive to Allah’s (S.W.T) will to leave Medina and Mecca; and he was obedient to rise. Therefore, Husain’s (A.S) intention was only to please Allah (S.W.T) and to accomplish his duty.
(Selected from "A Light from the Greatness of Imam Husain" by Grand Ayatullah Saafi Gulpaygani, with minor changes)
source : sibtayn