Grandson of the Prophet and martyr of Karbala (61/680). The al-Husayn Mosque in Cairo is a relic-shrine believed to hold his BLESSED HEAD — not his body. Per the Egyptian tradition the head went Karbala→Damascus→Ascalon and was transferred to Cairo in 548/1153. His body is agreed to be in Karbala; the head's location is disputed. Egypt's Dar al-Ifta treats this as historical, not creedal. (Sources: Egypt Dar al-Ifta; Wikipedia 'Al-Hussein Mosque'; al-Maqrizi.)