The Day of Arafah is an Islamic holiday that falls on the 9th day of Dhu al-Hijjah of the lunar Islamic Calendar. It is the holiest day in the Islamic calendar (the holiest night being The Night of Power), the second day of the Hajj pilgrimage, and the day after is the first day of the major Islamic holiday of Eid al-Adha.
At dawn of this day, Muslim pilgrims will make their way from Mina to a nearby hillside and plain called Mount Arafat and the Plain of Arafat. It was from this site that the prophet Muhammad gave one of his last sermons in the final year of his life. Some Muslims hold that part of the Quranic verse announcing that the religion of Islam had been perfected was revealed on this day.