Cross reference
Genesis 25:16
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.
Genesis 17:20
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 17:23
23 And Abraham took Ishmael his son, and all that were born in his house, and all that were bought with his money, every male among the men of Abraham's house; and circumcised the flesh of their foreskin in the selfsame day, as God had said unto him.