Genesis 21:6

God had promised that Sarah would have a son. And Sarah did not believe what God said. She laughed because she did not believe. (See Genesis 18:12.) After Isaac’s birth, Sarah laughed again. But then she laughed because she was very happy.

Abraham sends Hagar and Ishmael away

v8 The baby grew. And Sarah began to give solid food to him. So Abraham called many people to come to a big meal on the day when Isaac ate solid food. v9 Sarah saw Abraham’s other son, Ishmael, whose mother was Hagar the Egyptian. Ishmael was laughing at Isaac. v10 So Sarah said to Abraham, ‘Throw out this woman and her son. She is a slave. This slave-woman’s son shall not get any part of your wealth. That belongs to my son Isaac.’

v11 Sarah’s words about Abraham’s son made Abraham very unhappy. v12 But God said to Abraham, ‘Do not be unhappy about the boy and about your slave-woman. Do what Sarah tells you to do. Isaac’s *descendants will be called your *descendants. v13 And I will also make a nation from your slave-woman’s son, because he is your son too.’