Genesis 21:1-13

The LORD graciously remembered and visited Sarah as He had said, and the LORD did for her as He had promised. So Sarah conceived and gave birth to a son for Abraham in his old age, at the appointed time of which God had spoken to him. Abraham named his son Isaac (laughter), the son to whom Sarah gave birth. So Abraham circumcised his son Isaac when he was eight days old, just as God had commanded him. Abraham was a hundred years old when his son Isaac was born. Sarah said, “God has made me laugh; all who hear [about our good news] will laugh with me.” And she said, “Who would have said to Abraham that Sarah would nurse children? For I have given birth to a son by him in his old age.” [Heb 11:12] The child [Isaac] grew and was weaned, and Abraham held a great feast on the day that Isaac was weaned. Now [as time went on] Sarah saw [Ishmael] the son of Hagar the Egyptian, whom she had borne to Abraham, mocking [Isaac]. [Gal 4:29] Therefore she said to Abraham, “Drive out this maid and her son, for the son of this maid shall not be an heir with my son Isaac.” [Gal 4:28-31] The situation distressed Abraham greatly because of his son [Ishmael]. God said to Abraham, “Do not let it distress you because of Ishmael and your maid; whatever Sarah tells you, listen to her and do what she asks, for your descendants will be named through Isaac. [Rom 9:7] And I will also make a nation of [Ishmael] the son of the maid, because he is your descendant.”