People in cities and towns across Iran attended the rituals in mosques, Husseiniyas and other religious centers.
The 28th day of the month of Safar (the second month in the lunar Hijri calendar) marks the passing away of Prophet Muhammad (PBUH) as well as the martyrdom of Imam Hassan (AS), the second Shia Imam.
This year, the sad occasion fell on Sunday, October 27.
The martyrdom anniversary of Imam Reza (AS), the eighth Imam of Shias who was martyred on the last day of the month of Safar, will also be mourned by Shia Muslims around the world on Tuesday.