The LORD was good to Sarah and kept his promise. Although Abraham was very old, Sarah had a son exactly at the time God had said.  Abraham named his son Isaac, and when the boy was eight days old, Abraham circumcised him, just as the LORD had commanded.

Abraham was a hundred years old when Isaac was born, and Sarah said, "God has made me laugh.  Now everyone will laugh with me.  Who would have dared to tell Abraham that someday I would have a child?  But in his old age, I have given him a son."

The time came when Sarah no longer had to nurse Isaac, and on that day Abraham gave a big feast.