 A pilgrim's Hajj is considered invalid if they do not spend the afternoon on Arafah.As Husayn ibn Ali recited the prayer during the Hajj at Mount Arafah on 9 Dhu al-Hijjah, Muslims during the Hajj recite the Arafah prayer from Zuhr prayer to sunset.This day is called prayer day, specially for people who stand on Mount Arafah.