⁷ and not all of Abraham’s descendants are his true descendants. On the contrary, “It is through Isaac that descendants will be named for you.”^{[a] 8} That is, it is not merely the children born through natural descent who were regarded as God’s children, but it is the children born through the promise who were regarded as descendants. ⁹ For this is the language of the promise: “At this time I will return, and Sarah will have a son.”^[b]