Genesis 17:15-27 NLT
Then God said to Abraham, “Regarding Sarai, your wife—her name will no longer be Sarai. From now on her name will be Sarah. And I will bless her and give you a son from her! Yes, I will bless her richly, and she will become the mother of many nations. Kings of nations will be among her descendants.”
Then Abraham bowed down to the ground, but he laughed to himself in disbelief. “How could I become a father at the age of 100?” he thought. “And how can Sarah have a baby when she is ninety years old?” So Abraham said to God, “May Ishmael live under your special blessing!”
But God replied, “No—Sarah, your wife, will give birth to a son for you. You will name him Isaac, and I will confirm my covenant with him and his descendants as an everlasting covenant. As for Ishmael, I will bless him also, just as you have asked. I will make him extremely fruitful and multiply his descendants. He will become the father of twelve princes, and I will make him a great nation. But my covenant will be confirmed with Isaac, who will be born to you and Sarah about this time next year.” When God had finished speaking, he left Abraham.
On that very day Abraham took his son, Ishmael, and every male in his household, including those born there and those he had bought. Then he circumcised them, cutting off their foreskins, just as God had told him. Abraham was ninety-nine years old when he was circumcised, and Ishmael, his son, was thirteen. Both Abraham and his son, Ishmael, were circumcised on that same day, along with all the other men and boys of the household, whether they were born there or bought as servants. All were circumcised with him.
NLT: New Living Translation