Zil-Hijjah is the twelfth and final month of the Islamic lunar calendar. It holds great significance for Muslims, as it is the month in which the annual pilgrimage, known as Hajj, takes place. The Hajj is one of the Five Pillars of Islam and is obligatory for all Muslims who are physically and financially able to perform it at least once in their lifetime. The first ten days of Zil-Hijjah are considered particularly sacred, with the Day of Arafah occurring on the ninth day. This day is marked by fasting and prayer, while the tenth day is celebrated as Eid al-Adha, a festival commemorating the willingness of Ibrahim to sacrifice his son in obedience to God.