²³ His son by the slave woman was born according to the flesh,^(A) but his son by the free woman was born as the result of a divine promise.^(B)

¹¹ And by faith even Sarah, who was past childbearing age,^(A) was enabled to bear children^(B) because she^[a] considered him faithful^(C) who had made the promise.

⁷ Nor because they are his descendants are they all Abraham’s children. On the contrary, “It is through Isaac that your offspring will be reckoned.”^{[a](A) 8} In other words, it is not the children by physical descent who are God’s children,^(B) but it is the children of the promise who are regarded as Abraham’s offspring.^(C)

The Birth of Isaac

21 Now the Lord was gracious to Sarah^(A) as he had said, and the Lord did for Sarah what he had promised.^{(B) 2} Sarah became pregnant and bore a son^(C) to Abraham in his old age,^(D) at the very time God had promised him.^(E)

¹⁰ Then one of them said, “I will surely return to you about this time next year,^(A) and Sarah your wife will have a son.”^(B)

Now Sarah was listening at the entrance to the tent, which was behind him. ¹¹ Abraham and Sarah were already very old,^(C) and Sarah was past the age of childbearing.^{(D) 12} So Sarah laughed^(E) to herself as she thought, “After I am worn out and my lord^(F) is old, will I now have this pleasure?”

¹³ Then the Lord said to Abraham, “Why did Sarah laugh and say, ‘Will I really have a child, now that I am old?’^{(G) 14} Is anything too hard for the Lord?^(H) I will return to you at the appointed time next year,^(I) and Sarah will have a son.”^(J)

²⁸ Now you, brothers and sisters, like Isaac, are children of promise.^{(A) 29} At that time the son born according to the flesh^(B) persecuted the son born by the power of the Spirit.^(C) It is the same now.

¹⁵ God also said to Abraham, “As for Sarai^(A) your wife, you are no longer to call her Sarai; her name will be Sarah.^{(B) 16} I will bless her and will surely give you a son by her.^(C) I will bless her so that she will be the mother of nations;^(D) kings of peoples will come from her.”

¹⁷ Abraham fell facedown;^(E) he laughed^(F) and said to himself, “Will a son be born to a man a hundred years old?^(G) Will Sarah bear a child at the age of ninety?”^{(H) 18} And Abraham said to God, “If only Ishmael^(I) might live under your blessing!”^(J)

¹⁹ Then God said, “Yes, but your wife Sarah will bear you a son,^(K) and you will call him Isaac.^[a](L) I will establish my covenant with him^(M) as an everlasting covenant^(N) for his descendants after him.

¹⁸ Against all hope, Abraham in hope believed and so became the father of many nations,^(A) just as it had been said to him, “So shall your offspring be.”^{[a](B) 19} Without weakening in his faith, he faced the fact that his body was as good as dead^(C)—since he was about a hundred years old^(D)—and that Sarah’s womb was also dead.^{(E) 20} Yet he did not waver through unbelief regarding the promise of God, but was strengthened^(F) in his faith and gave glory to God,^{(G) 21} being fully persuaded that God had power to do what he had promised.^(H)

⁸ But what does it say? “The word is near you; it is in your mouth and in your heart,”^[a](A) that is, the message concerning faith that we proclaim: