This chapter Explains the covenant sign in detail. God establishes circumcision as the lasting mark of His covenant: every male in Abraham’s household, whether born into the family or acquired as a servant, must be circumcised. This act will serve as a physical reminder of belonging to God and participating in His promise. God stresses the seriousness of this sign—any uncircumcised male will be cut off from the covenant people. Then, the focus shifts to Sarai: God not only includes her in this covenant plan but also changes her name to Sarah, signaling her central role in the promise of descendants and nations.

In short: these verses tie God’s eternal covenant to a very tangible symbol—circumcision—binding Abraham’s household to Him in body as well as faith. At the same time, Sarah is lifted up as more than Abraham’s partner; she, too, is renamed and redefined as essential to God’s unfolding plan. Promise now has both sign and shared partnership, linking Abraham and Sarah together in covenant purpose.