Son of Hagar and Abraham, Ishmael's name means "God will hear" (Genesis 16:11). Ishmael's descendants are the Arabic peoples according to both Jewish and Arab tradition. His half-brother Isaac was the father of the Jewish nation. Since Abraham's wife was concerned about the firstborn status of Ishmael, she mistreated Hagar so that she and her son would leave Abraham's house in Genesis 16:6. In a later account, she commands Abraham to expel Ishmael (Genesis 21:10). The two arrive in Beersheva, and are faint with thirst when God promises that Ishmael will be made a great nation and shows them a nearby water source (Genesis 21:12-20) Ishmael had 12 sons with an Egyptian wife.
Sources: Bridger, David. Ed. The New Jewish Encyclopedia, NY: Behrman House, 1976; Navigating the Bible II