Imam (A) flatly refused to pay allegiance to Yazid, well knowing that giving 'Bay'at' to him would leave Islam and the Muslims in ruins. His famous answer to the governor of Yazid was, "A man like me can never give allegiance to a man like him."
The caravan of Imam Husain (A) had arrived in Karbala and their tents were pitched next to the river Euphrates. As his companions settled down, Imam Husain (A) took his brother Abbas (A) around the barren desert and pointed out the various places where each of his comrades would fall and be slain on the Day of Ashura.
The people living in the area were from the tribe of Bani Asad. Imam Husain (A) purchased the land of Karbala from them and then gifted it back to them. He then addressed the men of Bani Asad saying, "On the tenth of this month you will see our dead bodies lying on this plain with our heads severed and taken away. Please bury us, and when our devotees come to visit our graves, treat them with honour and point out to them the places of our burial."
Shia Muslims in a procession during the 10 day mourning period of Ashura