Genesis 17:9-19 TMB

9 And God said unto Abraham, "Thou shalt keep My covenant, therefore, thou and thy seed after thee in their generations.
10 This is My covenant which ye shall keep between Me and you and thy seed after thee: every manchild among you shall be circumcised.
11 And ye shall circumcise the flesh of your foreskin; and it shall be a token of the covenant between Me and you.
12 And he that is eight days old shall be circumcised among you, every manchild in your generations, he that is born in the house or bought with money from any stranger who is not of thy seed.
13 He that is born in thy house and he that is bought with thy money must be circumcised; and My covenant shall be in your flesh for an everlasting covenant.
14 And the uncircumcised manchild whose flesh of his foreskin is not circumcised, that soul shall be cut off from his people; he hath broken My covenant."
15 And God said unto Abraham, "As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be.
16 And I will bless her and give thee a son also by her. Yea, I will bless her, and she shall be a mother of nations; kings of people shall be of her."
17 Then Abraham fell upon his face and laughed, and said in his heart, "Shall a child be born unto him that is a hundred years old? And shall Sarah, who is ninety years old, bear?"
18 And Abraham said unto God, "O that Ishmael might live before Thee!"
19 And God said, "Sarah thy wife shall bear thee a son indeed, and thou shalt call his name Isaac; and I will establish My covenant with him for an everlasting covenant, and with his seed after him.