A patriarch of the Old Testament, Abraham was called by God to be the father of the people of Israel. His wife Sarah was childless until an advanced age, when she bore Abraham's heir Isaac (Genesis 17, 18, 21).
God tested Abraham's obedience by asking him to sacrifice Isaac, but at the last moment he sent an angel to save the boy. Abraham's willingness to sacrifice his son is seen as prefiguring God's sacrifice of Christ to redeem the world (Genesis 22).
Abraham's elder son Ishmael and his mother Hagar (Abraham's concubine) were expelled from the household by Sarah. They were helped by an angel and supposedly founded the Arabic tribes (Genesis 21).