WARNING: Video contains graphic content<br/> <br />Thousands of Shi'ite Muslims stream through a mosque in the Iraqi city of Kerbala.<br/> <br />They are celebrating one of the holiest days on the Islamic calendar - Ashura.<br/> <br />It marks the death over 1,300 years ago of Imam Hussein, the grandson of the Prophet Mohammed.<br/> <br />That led to the division of Islam into two sects - Sunni and Shi'ite - a schism that continues to plague the Islamic world.<br/> <br />Shi'ites across the Middle East consider Ashura a day of mourning.<br/> <br />Here in Lebanon, worshippers cut their heads and slap their wounds, a sign of solidarity with Hussein's suffering.<br/> <br />The ritual sefl-flagellation, though, is considered controversial.
