15 Then God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. 16 And I will bless her and also give you a son by her; then I will bless her, and she shall be a mother of nations; kings of peoples shall be from her.”
17 Then Abraham fell on his face and laughed, and said in his heart, “Shall a child be born to a man who is one hundred years old? And shall Sarah, who is ninety years old, bear a child?” 18 And Abraham said to God, “Oh, that Ishmael might live before You!”
19 Then God said: “No, Sarah your wife shall bear you a son, and you shall call his name Isaac; I will establish My covenant with him for an everlasting covenant, and with his descendants 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. He shall beget twelve princes, and I will make him a great nation. 21 But My covenant I will establish with Isaac, whom Sarah shall bear to you at this set time next year.” 22 Then He finished talking with him, and God went up from Abraham.
23 So 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 foreskins that very 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 And Ishmael his son was thirteen years old when he was circumcised in the flesh of his foreskin. 26 That very same day Abraham was circumcised, and his son Ishmael; 27 and all the men of his house, born in the house or bought with money from a foreigner, were circumcised with him.