You must have heard how Ibne Saad started the battle on the Ashura day.
You must also have heard that Imam Husain (a.s.) did not allow starting
hostilities from his side. This custom was followed without fail when the
opposite army was apparently Muslim. Imam Ali (a.s.) strictly followed
this custom. He used to say, “I would never initiate the battle. Let them
start the fighting. We would hit them later.”
Imam Husain (a.s.) also did not start the battle. Instead Umar bin Saad
called for his bow and arrows for seeking the pleasure of Ubaidullah Ibne
Ziyad. Umar bin Saad’s father was Saad bin Abi Waqqas, a renowned
archer during the early days of Islam. He (Umar) placed an arrow in his
bow, aimed at the camp of Husain and shouted:
“O people! Bear witness to Amir Ibne Ziyad that I was the first to
shoot at Husain’s camp to start the battle.”
The battle of Ashura started with an arrow and also ended with an arrow.
The poisonous arrow, which ended the battle, had hit the holy heart of
Imam Husain (a.s.). It pierced the Imam’s chest from front and came out
from behind. Thus, the Imam could not take it out from the front. It is
written that the Imam pulled it out from his back. After being hit by this
arrow. Imam Husain (a.s.) could not balance himself on the horseback
and he fell down. He did not have enough strength to get up.
Biharul Anwar, Vol. 55, Pg. 53.