Sarah concerning Ishmael, Abraham's biological son by Hagar, a slave-woman in Genesis 21:10: “Cast out this slave-woman with her son; for the son of this slave-woman shall not be heir with my son Isaac.” God tells Abraham to follow this injunction regardless of Abraham's sympathy for Ishmael (Genesis 21:12). So where Abraham might represent a humanizing tendency, God actually demands the more inhumane option.
