Genesis 21:3-7

Abraham named his son who was born to him, the son whom Sarah bore to him, Isaac.

Then Abraham circumcised his son Isaac when he was eight days old, as God had commanded him.

Now Abraham was a hundred years old when his son Isaac was born to him.

Sarah said, “God has made laughter for me; everyone who hears will laugh with me.”

And she said, “Who would have said to Abraham that Sarah would nurse children? Yet I have given birth to a son in his old age.”