In Iran, the Death of Prophet Muhammad and the Martyrdom of Imam Hasan are observed as a public holiday on Safar 28 every year. This day commemorates the death of Prophet Muhammad, who is regarded as the last prophet sent by God to all of humanity, and the martyrdom of his grandson, Imam Hasan, who was the second Shiite Imam. While Shiites observe the day with significance, Sunnites do not mark it as a special occasion. Imam Hasan, who briefly served as caliph, was poisoned, allegedly at the behest of Muawiya, and died on this date in 669. The observance includes various religious activities and reflections on the lives and teachings of these central Islamic figures.