In these words as well as in his testament the Imam made his mission known to the people. He said: "I am going to enjoin the people to do good and to restrain them from evil". What did he mean by this? Possibly most of the people who heard these words of the Imam imagined that he wanted to go to Kufa and tell the grocers and bakers of that city: "Do not weigh less. Do not sell bad curd and cheese and improperly baked bread to the people". Or that he might tell the merchants of Kufa not to charge interest. This would be restraining from evil! Or that he might tell the residents of Kufa: "Do not be careless about obligatory prayers. If you can afford you must go to Makkah and perform Haj". This would be enjoining to do good. But the Imam's object was much higher than this. Of course this kind of enjoining to do good and restraining from evil is something good and essential, but this task could be performed by the ulema of Kufa and did not necessitate the Holy Imam's going there. In fact Imam Husayn wanted to do something which none else could do. In the conditions then prevailing it was only he, who could perform a memorable deed whose freshness cannot fade with the passage of time, and which cannot be effaced from the pages of the history of Islam.
source : http://www.al-islam.org
