The Islamic nation should never forget the event of Ashura, which is a lesson and a source of guidance. Islam is definitely alive because of the event of Ashura and the efforts of Hussain ibn Ali (pbuh). Prophet Muhammad (pbuh) stated, "And I am from Hussain." This statement means that Hussain (pbuh) continued the path of the Holy Prophet (pbuh), and he continued to promote Islam after him. If it had not been for the event of Ashura, and if these great sacrifices had not been made in the history of Islam, this valuable experience and this practical lesson would not have remained for the Islamic nation. Islam would have definitely deviated from its path - as many religions before Islam did. Nothing would have remained from the reality and essence of Islam.
Their bodies were covered in blood and dirt. They made sacrifices and they laid down their lives. The family of the Holy Prophet (pbuh) and Imam Ali (pbuh) were imprisoned. Those events are very tragic and very difficult to tolerate. But what was achieved on the Day of Ashura was so great and glorious that it made it easy for Imam Hussain (pbuh), his followers and his household to endure the sufferings.
Ayatollah Khamenei Nov. 21, 2012