Dhu al-Hijjah is the twelfth and final month of the Islamic (Hijri) calendar and one of its four sacred months; its name means the master of the pilgrimage, for it is the month of the Hajj to Mecca, the great pilgrimage that is one of the five pillars of Islam. Its rites reach their height on the ninth, the Day of Arafah, and the tenth is Eid al-Adha, the feast of the sacrifice, commemorating Abraham's willingness to sacrifice his son, kept by pilgrims and by Muslims everywhere with the sacrifice of an animal and the sharing of its meat, the greater of the two Islamic feasts. The Islamic calendar is purely lunar, so the Hajj season moves through the solar year over time. These are the observances of the Islamic tradition, in which the year closes with its holiest pilgrimage and feast.
Dhu al-Hijjah, the last and one of the four sacred months, holds the Hajj, the pilgrimage to Mecca obligatory once in a lifetime for every Muslim who is physically and financially able, concentrated in the first ten to thirteen days and centred on the Day of Arafah, the ninth, when pilgrims gather at the plain of Arafat in what is widely regarded as the pilgrimage's central rite. The tenth opens Eid al-Adha, the Festival of Sacrifice, commemorating the willingness of Ibrahim to sacrifice his son at God's command, a narrative the Quran recounts without naming the son directly, though most Islamic tradition identifies him as Ismail, in contrast to the Genesis account's naming of Isaac.