Genesis 21:5-12

5 aAbraham was a hundred years old when his son Isaac was born to him. 6And Sarah said, bGod has made laughter for me; everyone who hears will laugh over me.” 7And she said, “Who would have said to Abraham that Sarah would nurse children? cYet I have borne him a son in his old age.”

God Protects Hagar and Ishmael

8And the child grew and was weaned. And Abraham made a great feast on the day that Isaac was weaned. 9But Sarah dsaw the son of Hagar the Egyptian, whom she had borne to Abraham, elaughing.
Possibly  laughing in mockery
10So she said to Abraham, g“Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac.” 11And the thing was very displeasing to Abraham on account of his son. 12But God said to Abraham, “Be not displeased because of the boy and because of your slave woman. Whatever Sarah says to you, do as she tells you, for hthrough Isaac shall your offspring be named.
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