Genesis 17:10-27

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 asign of the covenant between me and you. 12He who is beight days old among you shall be circumcised. Every male throughout your generations, whether born in your house or cbought 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
 Sarai and  Sarah mean princess
shall be her name.
16I will bless her, and moreover, I will egive
Hebrew have given
you a son by her. I will bless her, and gshe shall become nations; kings of peoples shall come from her.”
17Then Abraham hfell on his face iand laughed and said to himself, “Shall a child be born to a man who is a hundred years old? Shall Sarah, who is ninety years old, bear a child?” 18And Abraham said to God, “Oh that Ishmael might live before you!” 19God said, “No, but jSarah your wife shall bear you a son, and you shall call his name kIsaac.
 Isaac means he laughs
I will establish my covenant with him as an everlasting covenant for his offspring after him.
20As for Ishmael, I have heard you; behold, I have blessed him and will make him fruitful and mmultiply him greatly. He nshall father twelve princes, and oI will make him into a great nation. 21But pI will establish my covenant with Isaac, qwhom Sarah shall bear to you at this time next year.”

22When he had finished talking with him, rGod 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.

Leviticus 12:3

3And on the seighth day the flesh of his foreskin shall be circumcised.

John 7:22

22 tMoses gave you circumcision (not that it is from Moses, but ufrom the fathers), and you circumcise a man on the Sabbath.
Copyright information for ESV