Contradiction with Genesis 17:19
Genesis 17:19 specifies that God promises Sarah will bear a son and that his name shall be Isaac, which aligns with Genesis 21:3; not a contradiction.
Genesis 17:19: And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, [and] with his seed after him.
Contradiction with Genesis 17:17
This verse depicts Abraham doubting God's promise of a son at such an old age, while Genesis 21:3 shows the fulfillment of that promise.
Genesis 17:17: Then Abraham fell upon his face, and laughed, and said in his heart, Shall [a child] be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear?
Contradiction with Genesis 16:15
States that Hagar bore Abraham a son, Ishmael, suggesting Hagar's son came before the promise was fulfilled to Sarah, showcasing familial tensions and differing narratives but not a direct contradiction.
Genesis 16:15: And Hagar bare Abram a son: and Abram called his son's name, which Hagar bare, Ishmael.
Contradiction with Hebrews 11:11
Sarah's faith is credited for her conceiving, showing belief where Genesis 21:3 reports the event, potentially highlighting human doubt.
Hebrews 11:11: Through faith also Sara herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised.
Contradiction with Genesis 21:10
Sarah tells Abraham to cast out Hagar and Ishmael, contrasting with the joy of the birth of Isaac in Genesis 21:3.
Genesis 21:10: Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, [even] with Isaac.