Genesis 17:15-27
15 God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but her name shall be Sarah. 16 I will bless her, and moreover I will give you a son by her. Yes, I will bless her, and she will be a mother ...
17 Then Abraham fell on his face, and laughed, and said in his heart, “Will a child be born to him who is one hundred years old? Will Sarah, who is ninety years old, give birth?” 18 Abraham said to God, “Oh that Ishmael might live before you!”
19 God said, “No, but Sarah, your wife, will bear you a son. You shall call his name Isaac.[a] I will establish my covenant with him for an everlasting covenant for his offspring after him. 20 As for Ishmael, I have heard you. Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly. He will become the father of twelve princes, and I will make him a great nation. 21 But I will establish my covenant with Isaac, whom Sarah will bear to you at this set time next year.”
22 When he finished talking with him, God went up from Abraham. 23 Abraham took Ishmael his son, all who were born in his house, and all who were bought with his money: every male among the men of Abraham’s house, and circumcised the flesh of their foreskin in the same day, as God had said to him. 24 Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. 25 Ishmael, his son, was thirteen years old when he was circumcised in the flesh of his foreskin. 26 In the same day both Abraham and Ishmael, his son, were circumcised. 27 All the men of his house, those born in the house, and those bought with money from a foreigner, were circumcised with him.