God also said to Abraham, "As for you, you and your offspring after you throughout their generations are to keep My covenant.
This is My covenant, which you are to keep, between Me and you and your offspring after you: Every one of your males must be circumcised.
You must circumcise the flesh of your foreskin to serve as a sign of the covenant between Me and you.
References for Genesis 17:11
Throughout your generations, every male among you at eight days old is to be circumcised. This includes a slave born in your house and one purchased with money from any foreigner. The one who is not your offspring,
a slave born in your house, as well as one purchased with money, must be circumcised. My covenant will be in your flesh as an everlasting covenant.
If any male is not circumcised in the flesh of his foreskin, that man will be cut off from his people; he has broken My covenant."
God said to Abraham, "As for your wife Sarai, do not call her Sarai, for Sarah will be her name.
References for Genesis 17:15
I will bless her; indeed, I will give you a son by her. I will bless her, and she will produce nations; kings of peoples will come from her."
Abraham fell to the ground, laughed, and thought in his heart, "Can a child be born to a hundred-year-old man? Can Sarah, a ninety-year-old woman, give birth?"
References for Genesis 17:17
So Abraham said to God, "If only Ishmael could live in Your presence!"
But God said, "No. Your wife Sarah will bear you a son, and you will name him Isaac. I will confirm My covenant with him as an everlasting covenant for his offspring after him.
References for Genesis 17:19