Genesis 21:1-9

The LORD kept his word and did for Sarah exactly what he had promised. She became pregnant, and she gave birth to a son for Abraham in his old age. This happened at just the time God had said it would. And Abraham named their son Isaac. Eight days after Isaac was born, Abraham circumcised him as God had commanded. Abraham was 100 years old when Isaac was born. And Sarah declared, “God has brought me laughter. All who hear about this will laugh with me. Who would have said to Abraham that Sarah would nurse a baby? Yet I have given Abraham a son in his old age!” When Isaac grew up and was about to be weaned, Abraham prepared a huge feast to celebrate the occasion. But Sarah saw Ishmael—the son of Abraham and her Egyptian servant Hagar—making fun of her son, Isaac.