Public Holiday. Eid al-Adha (Id ul-Adha) is a four-day Islamic festival starting on the 10th day of the month of Dhul Hijja (Thou al-Hijja) to commemorate the willingness of Ibrahim (Abraham) to sacrifice his son.id al-Adha is an Islamic festival to commemorate the willingness of Ibrahim (also known as Abraham) to follow Allah's (God's) command to sacrifice his son Ishmael. Muslims around the world observe this event.