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When readers first meet Abraham in Genesis 11, his name is Abram. God re-names him with the promise that he will be the father (Hebrew av) of a multitude (Hebrew hamon) of peoples (Genesis 17:5). His wife and half-sister Sarai is also renamed (Sarah).
Before this renaming, Sarai is infertile. Abram’s first child is conceived by Hagar, a slavewoman whom Abram takes as a secondary wife. This child is named Ishmael (Hebrew Yishmael, ‘God hears’). Sarai has Hagar and Ishmael sent away, though God intervenes to provide water for the mother and child (who are alone in the desert). God then makes an agreement with Abram: ‘Walk before me and be blameless’, God says ‘that I may make my covenant with you and multiply you.’ Sarai, now to be known as Sarah, conceives and gives birth to Isaac.
Another significant relative is Abraham’s nephew, Lot.
One of the most famous episodes in Abraham’s story happens when God tells him to sacrifice his son (Genesis 22). In Jewish tradition, this passage is known as the Akedah or ‘Binding’ of Isaac. Christians commonly refer to it as the ‘Sacrifice’ of Isaac although Isaac is not actually killed. The narrative also appears in the Qur’an (Sura 27); because the Qur’an does not identify the son that Abraham must kill, the victim is commonly understood to be Ishmael.
Blenkinsopp, Joseph. Abraham: The Story of a Life. Grand Rapids, MI; Cambridge, England: Eerdmans, 2015.