Imam Hussein was the powerful arm of the religion of Allah
There is a saying from Imam of the time about Imam Hussein which is completely astonishing and appalling for those who can fathom this matter out. The twelfth Imam and our other Imams do not have such an interpretation for anyone else. They say: our Hussein is the Arm of the religion of Allah, and if this arm did not work, the religion of Allah would vanish into thin air. The mankind's strength is in his arms, the one who lifts weights, he is, indeed, using the power of his arms, the one who is wrestling, he does it by using the strength in his arms. The Imam of the time says: Imam Hussein is the arm of Islam- namely, this arm kept the religion and stood against the Umayyad infidelity as well as the polytheism of Saqifa [i] and defeated them.
[i] significant for being the site of a hasty assembly of some companions of Muhammad, the Prophet of Islam, where they decided about the successor to the Prophet right after his death, a controversial decision that is believed to have originated the oldest division in Islam between the Shia and Sunni denominations.)
source : erfan.ir