21 Now the Lord was gracious to Sarah as he had said, and the Lord did for Sarah what he had promised. 2 Sarah became pregnant and bore a son to Abraham in his old age, at the very time God had promised him. 3 Abraham gave the name Isaac to the son Sarah bore him. 4 When his son Isaac was eight days old, Abraham circumcised him, as God commanded him. 5 Abraham was a hundred years old when his son Isaac was born to him.6 Sarah said, “God has brought me laughter, and everyone who hears about this will laugh with me.” 7 And she added, “Who would have said to Abraham that Sarah would nurse children? Yet I have borne him a son in his old age.”8 The child grew and was weaned, and on the day Isaac was weaned Abraham held a great feast. 9 But Sarah saw that the son whom Hagar the Egyptian had borne to Abraham was mocking, 10 and she said to Abraham, “Get rid of that slave woman and her son, for that woman’s son will never share in the inheritance with my son Isaac.”
11 The matter distressed Abraham greatly because it concerned his son. 12 But God said to him, “Do not be so distressed about the boy and your slave woman. Listen to whatever Sarah tells you, because it is through Isaac that your offspring will be reckoned. 13 I will make the son of the slave into a nation also, because he is your offspring.”
So this is the second time Sarah demands that Hagar and Ishmael (who for some reason has misplaced his name) be driven out into the desert. To be clear, Hagar is Sarah's slave, so yeah she can do this. What exactly did Hagar see Ishmael doing?
14 Early the next morning Abraham took some food and a skin of water and gave them to Hagar. He set them on her shoulders and then sent her off with the boy. She went on her way and wandered in the Desert of Beersheba.
15 When the water in the skin was gone, she put boy under one of the bushes. 16 Then she went off and sat down about a bowshot away, for she thought, “I cannot watch the boy die.” And as she sat there, she began to sob.
17 God heard the boy crying, and the angel of God called to Hagar from heaven and said to her, “What is the matter, Hagar? Do not be afraid; God has heard the boy crying as he lies there. 18 Lift the boy up and take him by the hand, for I will make him into a great nation.”
19 Then God opened her eyes and she saw a well of water. So she went and filled the skin with water and gave the boy a drink.
20 God was with the boy as he grew up. He lived in the desert and became an archer. 21 While he was living in the Desert of Paran, his mother got a wife for him from Egypt.
Now this is extremely weird. Ishmael (who again has become nameless), is apparently an infant, who can be carried on his mother's shoulder and put under a bush to die. He is in fact at least 14 years old, if you've been paying attention. He was already 13 when he was circumcised. (Genesis 17:25) But the Bible is the literally true, inerrant word of God.