Genesis 21:3-13

3 And Abraham called the name of his son that was born unto him, whom Sarah bore to him, Isaac.
4 And Abraham circumcised his son Isaac being eight days old as God had commanded him.
5 And Abraham was one hundred years old when his son Isaac was born unto him.
6 Then Sarah said, God has made me to laugh so that all that hear will laugh with me.
7 And she said, Who would have said unto Abraham, that Sarah should have given children suck? For I have born him a son in his old age.
8 And the child grew and was weaned, and Abraham made a great banquet the day that Isaac was weaned.
9 And Sarah saw the son of Hagar the Egyptian, whom she had born unto Abraham, mocking.
10 Therefore she said unto Abraham, Cast out this bondwoman and her son; for the son of this bondwoman shall not be heir with my son, even with Isaac.
11 And the thing was very grievous in Abraham’s sight because of his son.
12 Then God said unto Abraham, Let it not be grievous in thy sight because of the lad and because of thy bondwoman; in all that Sarah has said unto thee, hearken unto her voice; for in Isaac shall thy seed be called.
13 And also of the son of the bondwoman I will make a nation because he is thy seed.