Mu'awiya made his son Yazid heir to the caliphate; Muhammad's grandson al-Husayn refused to swear and was killed at Karbala with most of his family's men

Al-Husayn was the son of Ali and of Muhammad's daughter Fatima (story 22). The caliph Mu'awiya, founder of the Umayyad dynasty, had made the people swear that his son Yazid would be his heir. Al-Tabari's history says that when Yazid succeeded in April 680, his first concern was to get that oath from those who had refused it. Al-Husayn and Abd Allah ibn al-Zubayr refused and left Medina for Mecca the same night. Kufans in Iraq wrote inviting al-Husayn. His cousin Muslim ibn Aqil reported that 12,000 of them had sworn to him. Yazid's governor, Ubaydallah ibn Ziyad, found Muslim and had him killed. Al-Husayn went on toward Iraq, and an army under Umar ibn Sa'd stopped him at Karbala. Umar refused the three proposals al-Husayn offered. On the morning of 10 Muharram, al-Husayn had 32 horsemen and 40 foot soldiers. He was killed with most of the men of his family. Seventy-two heads were sent to Ibn Ziyad, who poked al-Husayn's head with his cane; al-Bukhari records the same scene. Ibn Ziyad ordered al-Husayn's son Ali beheaded, then let him go with the women. The women and children were taken to Yazid in Damascus. Yazid said that had he faced al-Husayn himself, he would not have killed him. Al-Husayn's shrine stands in Karbala. The caliph al-Mutawakkil destroyed it in 850, and Wahhabi raiders sacked it in 1802^†. Up to 35 million pilgrims visit at Arbaeen each year^†.