Contradiction with Genesis 21:12
Genesis 17:16 states that Sarah will be a mother of nations, yet Genesis 21:12 suggests that Abraham's descendants will be named through Isaac, implying a narrower scope than "nations."
Genesis 21:12: And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called.
Contradiction with Judges 11:1-2
Genesis 17:16 promises Sarah will be the mother of nations, yet in Judges 11:1-2, Jephthah is ostracized as the son of a harlot, highlighting a contradiction in familial unity or acceptance.
Judges 11:1-2: Now Jephthah the Gileadite was a mighty man of valour, and he [was] the son of an harlot: and Gilead begat Jephthah. [Jephthah: Gr. Jephthae] [an harlot: Heb. a woman an harlot]
Contradiction with 1 Kings 11:1-2
Genesis 17:16 prophesies Sarah as a mother of kings, while 1 Kings 11:1-2 discusses Solomon's foreign wives, implying the dilution of the nation's unity.
1 Kings 11:1-2: But king Solomon loved many strange women, together with the daughter of Pharaoh, women of the Moabites, Ammonites, Edomites, Zidonians, [and] Hittites; [together...: or, beside]
Contradiction with Matthew 1:2-3
Genesis 17:16 discusses Sarah's descendants as leaders, but Matthew 1:2-3 lists a genealogy including Judah and his brothers, where leadership roles shift away from Sarah's immediate line.
Matthew 1:2-3: Abraham begat Isaac; and Isaac begat Jacob; and Jacob begat Judas and his brethren;