Gn 17:1, 9-10, 15-22

When Abram was ninety-nine years old, the LORD appeared to him
and said: “I am God the Almighty.
Walk in my presence and be blameless.”

God also said to Abraham:
“On your part, you and your descendants after you
must keep my covenant throughout the ages.
This is my covenant with you and your descendants after you
that you must keep:
every male among you shall be circumcised.”

God further said to Abraham:
“As for your wife Sarai, do not call her Sarai;
her name shall be Sarah.
I will bless her, and I will give you a son by her.
Him also will I bless; he shall give rise to nations,
and rulers of peoples shall issue from him.”
Abraham prostrated himself and laughed as he said to himself,
“Can a child be born to a man who is a hundred years old?
Or can Sarah give birth at ninety?”
Then Abraham said to God,
“Let but Ishmael live on by your favor!”
God replied: “Nevertheless, your wife Sarah is to bear you a son,
and you shall call him Isaac.
I will maintain my covenant with him as an everlasting pact,
to be his God and the God of his descendants after him.
As for Ishmael, I am heeding you: I hereby bless him.
I will make him fertile and will multiply him exceedingly.
He shall become the father of twelve chieftains,
and I will make of him a great nation.
But my covenant I will maintain with Isaac,
whom Sarah shall bear to you by this time next year.”
When he had finished speaking with him, God departed from Abraham.