Genesis 21:1-3 Young's Literal Translation (YLT)
21 And Jehovah hath looked after Sarah as He hath said, and Jehovah doth to Sarah as He hath spoken;
2 and Sarah conceiveth, and beareth a son to Abraham, to his old age, at the appointed time that God hath spoken of with him;
3 and Abraham calleth the name of his son who is born to him, whom Sarah hath born to him -- Isaac;
Genesis 21:1-3 New 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.