After the martyrdom his brother Hasan (as) Husayn (as) took...

After the martyrdom his brother Hasan (as) Husayn (as) took the mantle of Imamate and spiritual guidance of the Ummah. It is during this period that during one of his journeys to Makka for pilgrimage, his famous Duas (Supplication) of Arafah became famous. This is a Dua which at the place of Arafat during the Hajj ritual that Imam recited and many pilgrims heard it and instantly memorised it as was the practice of the people of that time.