According to the Biblical story, Ishmael was 13, and Abram was 100, when Sarai finally conceived and bore Abram his legitimate son, Isaac. By then, Abram had been renamed Abraham (“father of nations,” though the translation from Hebrew isn’t entirely airtight) by God himself, and Sarai renamed Sarah (a more confusing change, according to the Armstrong Institute of Biblical Archeology). Before Isaac’s birth, God confirmed with Abraham that Ishmael would not be the line of Abraham’s descendants through whom God would make his covenant. But God also said of Ishmael, “I will surely bless him … he will be the father of twelve rulers, and I will make him into a great nation.”
While Hagar’s angel had foretold strife between Ishmael and his brothers, Isaac never really knew his older sibling. During a feast held to celebrate Isaac’s weaning, Ishmael’s mocking attitude upset Sarah. She demanded that Abraham, who loved his eldest son, cast him and Hagar away. This Abraham was loathe to do until reassured by God of the promise to make Ishmael a great patriarch. The next day, he gave Hagar her freedom, supplied her and Ishmael with provisions, and sent them on their way.
Hagar led her son into the desert of Beersheba and soon resigned herself to death. Unwilling to watch Ishmael die, she left him under a bush and wandered off. Both began to cry until the angel of God returned to Hagar and told her they would not die.