Contradiction with Genesis 17:16
In Genesis 15:3, Abram expresses doubt about having his own offspring, yet in Genesis 17:16, God promises that Sarah will bear a son, contradicting Abram's earlier doubt.
Genesis 17:16: And I will bless her, and give thee a son also of her: yea, I will bless her, and she shall be [a mother] of nations; kings of people shall be of her. [she...: Heb. she shall become nations]
Contradiction with Genesis 21:2
Genesis 15:3 shows Abram's concern about not having an heir, but Genesis 21:2 reports the birth of his son Isaac, contradicting Abram’s earlier concern.
Genesis 21:2: For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him.
Contradiction with Galatians 4:22
Genesis 15:3 suggests Abram's heir would be from his household only, whereas Galatians 4:22 mentions two sons, one by a bondwoman and another by a free woman, highlighting a contradiction in who the heir would be.
Galatians 4:22: For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman.