By faith Sarah herself also received strength to conceive seed, and she bore a child when she was past the age, because she judged Him faithful who had promised.
Then He gave him the covenant of circumcision; and so Abraham begot Isaac and circumcised him on the eighth day; and Isaac begot Jacob, and Jacob begot the twelve patriarchs.
And He said, “I will certainly return to you according to the time of life, and behold, Sarah your wife shall have a son.” (Sarah was listening in the tent door which was behind him.)
Then God said: “No, Sarah your wife shall bear you a son, and you shall call his name Isaac; I will establish My covenant with him for an everlasting covenant, and with his descendants after him.
Then I took your father Abraham from the other side of the River, led him throughout all the land of Canaan, and multiplied his descendants and gave him Isaac.