Genesis 17:20
And as for Ishmael, I have heard thee: 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 25:16
These are the sons of Ishmael, and these are their names, by their towns, and by their castles; twelve princes according to their nations.