Genesis 21:1-7New International Version (NIV)

The Birth of Isaac

21 Now the Lord was gracious to Sarah as he had said, and the Lord did for Sarah what he had promised. ² Sarah became pregnant and bore a son to Abraham in his old age, at the very time God had promised him. ³ Abraham gave the name Isaac^[a] to the son Sarah bore him. ⁴ When his son Isaac was eight days old, Abraham circumcised him, as God commanded him. ⁵ Abraham was a hundred years old when his son Isaac was born to him.

⁶ Sarah said, “God has brought me laughter, and everyone who hears about this will laugh with me.” ⁷ And she added, “Who would have said to Abraham that Sarah would nurse children? Yet I have borne him a son in his old age.”