Addressing the simpleminded, shallow and breaching people in Kufa, Imam Sadjad (A.S) said: "O people! I put you on your oath to tell me in the name of Allah, whether you know that at one time you wrote letters to my father and then deceived him. You made firm promises with him and then rose to fight against him. May Allah destroy you, may you reap the harvest of your misdeeds in both the worlds, and may you be disgraced for the indecent policy which you have adopted. How will you face the Prophet of Allah when you are brought before him on the Day of Judgment and with which eyes will you look at him? At that time the Holy Prophet will tell you: "You have killed my children and behaved towards me dishonorably. You are not my followers".
These few sentences of the Imam changed the thinking of the people of Kufa and the smiling faces of those persons who had mostly come to see the prisoners blushed with shame. They tried to control themselves but could not do so. At last the groanings and lamentations of the people could be heard from different sides.[i]
Imam Sajjad's sermon in Kufa included the following:
1- Introducing himself and his progeny 2- Narrating the sorrowful story of Karbala tragedy 3-Expressing complaints to the people of Kufa on writing letters to Imam Hussein (A.S) and breaking their promise
source : www.tebyan.net