Genesis 21:1-7

1Now the LORD attended to Sarah as He had said, and the LORD did for Sarah what He had promised. 2So Sarah conceived and bore a son to Abraham in his old age, at the very time God had promised.

3And Abraham gave the name Isaac1 to the son Sarah bore to him. 4When his son Isaac was eight days old, Abraham circumcised him, as God had commanded him. 5Abraham was a hundred years old when his son Isaac was born to him.

6Then Sarah said, “God has made me laugh, and everyone who hears of this will laugh with me.” 7She added, “Who would have told Abraham that Sarah would nurse children? Yet I have borne him a son in his old age.”