Genesis 17
Abraham and the Covenant of Circumcision
1When Abram was ninety-nine years old the LORD appeared to Abram and said to him, "I am God Almighty;
9And God said to Abraham, "As for you, you shall keep my covenant, you and your offspring after you throughout their generations. 10This is my covenant, which you shall keep, between me and you and your offspring after you: Every male among you shall be circumcised. 11You shall be circumcised in the flesh of your foreskins, and it shall be a sign of the covenant between me and you. 12He who is eight days old among you shall be circumcised. Every male throughout your generations, whether born in your house or bought with your money from any foreigner who is not of your offspring, 13both he who is born in your house and he who is bought with your money, shall surely be circumcised. So shall my covenant be in your flesh an everlasting covenant. 14Any uncircumcised male who is not circumcised in the flesh of his foreskin shall be cut off from his people; he has broken my covenant."
Isaac's Birth Promised
15And God said to Abraham, "As for Sarai your wife, you shall not call her name Sarai, but Sarah
22When he had finished talking with him, God went up from Abraham. 23Then Abraham took Ishmael his son and all those born in his house or bought with his money, every male among the men of Abraham's house, and he circumcised the flesh of their foreskins that very day, as God had said to him. 24Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. 25And Ishmael his son was thirteen years old when he was circumcised in the flesh of his foreskin. 26That very day Abraham and his son Ishmael were circumcised. 27And all the men of his house, those born in the house and those bought with money from a foreigner, were circumcised with him.