Abraham, in Islam, is a prophet and messenger of God and is an ancestor to the Ishmaelite Arabs and Israelites. Abraham plays a prominent role as an example of faith in Judaism, Christianity, and Islam. In Muslim belief, Abraham fulfilled all the commandments and trials wherein God nurtured him throughout his lifetime. As a result of his unwavering faith in God, Abraham was promised by God to be a leader to all the nations of the world. The Quran extols Abraham as a model, an exemplar, obedient and not an idolater. In this sense, Abraham has been described as representing "primordial man in universal surrender to the Divine Reality before its fragmentation into religions separated from each other by differences in form". Most Muslims believe that the Kaaba in Mecca was built by Abraham and his son Ishmael as the first house of worship on earth. The Islamic holy day 'Eid ul-Adha is celebrated in commemoration of Abraham's willingness to sacrifice his son on God's command, as well as the end of the Hajj pilgrimage to the Kaaba.