People of Iran annually observe the public holiday of Martyrdom of Imam Reza.
This day takes place on Safar 28.
Muhammad is one of the central figures of Islam. He is the prophet and messenger of God and Muslims believe, that he was the last prophet sent by God to the mankind.
Hasan ibn Ali (Imam Reza) was Muhammad's grandson, the son of Ali and Muhammad's daughter Fatimah.
He was also the second Shiite Imam.
He was caliph from June to July in 661, but later he passed the power to Muawiya and moved to Medina.
According to the agreement, after the Muawiya's death Hasan would become the caliph again, but Muawiya nominated his son Yazid to be his heir.
Hasan was poisoned by one of his wives, that was arranged by Muawiya.
Imam Reza died on Safar 28, 669