In Context

15 And God said to Abraham, As for Sarai your wife, you shall not call her name Sarai, but Sarah shall her name be.

16 And I will bless her, and give you a son also of her: yes, I will bless her, and she shall be a mother of nations; kings of people shall be of her.

17 Then Abraham fell on his face, and laughed, and said in his heart, Shall a child be born to him that is an hundred years old? and shall Sarah, that is ninety years old, bear?

18 And Abraham said to God, O that Ishmael might live before you!

19 And God said, Sarah your wife shall bear you a son indeed; and you shall call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.

20 And as for Ishmael, I have heard you: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation.

Genesis 17:18 in Other Translations