It’s in the Bible
Three of the world’s major religions claim Abraham as their father. Genesis tells us that at God’s command, Abraham, when he was 75, left his home and wealth in search of a land that God promised. After many years and he did not have an heir, his wife Sarah encouraged him to have a son via her maidservant, Hagar, who conceived and bore him a son whom they named Ishmael.
And when Abraham was 99 years old, the Lord appeared to him and said, “I will make my covenant between me and thee and will multiply thee exceedingly. And I will give unto thee and to thy seed after thee, the land wherein thou art a stranger, all the land of Canaan, for an everlasting possession; and I will be their God.” (Genesis 17:2-8) Fourteen years after Ishmael was born, God said, “Sarah, thy wife, shall bear thee a son and thou shalt call his name Isaac, and I will establish my covenant with him for an everlasting covenant and with his seed after him.” (Genesis 17:19) Modern-day Jews trace their ancestry to Isaac, the son of promise, who had a son called Jacob. It was Jacob whose name God changed to Israel. In the Old Testament, God is repeatedly called the God of Abraham, Isaac, and Jacob.
God spoke to Hagar, even before he was born, describing the temperament of Ishmael and what the future held for him: “He will be a wild donkey of a man; his hand will be against everyone and everyone’s hand against him, and he will live in hostility toward all his brothers.” (Genesis 16:12) Abraham’s eldest son, Ishmael, is the progenitor of modern-day Arabs. The ensuing contest between Isaac and Ishmael to gain the upper hand, this “jihad” of individual and national proportions, both claiming to be Abraham’s legitimate heir, is the story of the Middle East.
And Muhammad knew his history, the Koran says: “And remember when Moses said unto his people, the Israelites: ‘O my people? Remember Allah’s favor unto you, how He placed among you prophets and He made you kings and gave you that which He gave not to any (Other) of (His) creatures. O my people! Go into that holy land which Allah hath ordained for you.'” (Surah 5:30-21)