God's Contract with Abraham

You are to safeguard my contract, you and your descendants after you, throughout their generations. This is my contract between me and you and your descendants after you which you will safeguard: Every male among you is to be circumcised. You are to circumcise the flesh of your foreskin. It will be a sign of the contract between me and you. You are to circumcise every male among you at eight days old throughout your generations - house-born or money-bought from any foreigner who is not of your descendants. Your house-born and your money-bought must be circumcised, so my contract will be in your flesh as an everlasting contract. As for an uncircumcised male who does not circumcise the flesh of his foreskin, his soul will be cut off from his people - he has breached my contract.
- Genesis 17:9-14