There is a lot of confusion about what happened to Ishmael. The Taurat, written 3500 years ago by the prophet Musa (PBUH), helps clarify this for us. Allah had promised Ibrahim (PBUH) that he would bless him and make his descendants as many as the sand on the seashore (see here). Ibrahim (PBUH) finally obtained two sons by his two wives, but a rivalry between them forced him to send Hagar and Ishmael away. This rivalry occurred in two stages. The first stage occurred after the birth of Ishmael and before the birth of Isaac. Here is what the Taurat says about this rivalry and how Allah protected Hagar, appeared to her and gave His blessing to Ishmael (PBUH).
Now Sarai, Abram’s wife, had borne him no children. But she had an Egyptian slave named Hagar; 2 so she said to Abram, “The LORD has kept me from having children. Go, sleep with my slave; perhaps I can build a family through her.”
Abram agreed to what Sarai said. 3 So after Abram had been living in Canaan ten years, Sarai his wife took her Egyptian slave Hagar and gave her to her husband to be his wife. 4 He slept with Hagar, and she conceived.
When she knew she was pregnant, she began to despise her mistress. 5 Then Sarai said to Abram, “You are responsible for the wrong I am suffering. I put my slave in your arms, and now that she knows she is pregnant, she despises me. May the LORD judge between you and me.”
6 “Your slave is in your hands, ” Abram said. “Do with her whatever you think best.” Then Sarai mistreated Hagar; so she fled from her.
7 The angel of the LORD found Hagar near a spring in the desert; it was the spring that is beside the road to Shur. 8 And he said, “Hagar, slave of Sarai, where have you come from, and where are you going?”
“I’m running away from my mistress Sarai,” she answered.
9 Then the angel of the LORD told her, “Go back to your mistress and submit to her.” 10 The angel added, “I will increase your descendants so much that they will be too numerous to count.”
11 The angel of the LORD also said to her: “You are now pregnant and you will give birth to a son. You shall name him Ishmael, for the LORD has heard of your misery. 12 He will be a wild donkey of a man; his hand will be against everyone and everyone’s hand against him, and he will live in hostility toward all his brothers. ”
13 She gave this name to the LORD who spoke to her: “You are the God who sees me, ” for she said, “I have now seen the One who sees me.” 14 That is why the well was called Beer Lahai Roi; it is still there, between Kadesh and Bered.
15 So Hagar bore Abram a son, and Abram gave the name Ishmael to the son she had borne. 16 Abram was eighty-six years old when Hagar bore him Ishmael.
We see that Hagar was a prophetess since she spoke with the LORD. He that told her the name of her son was to be Ishmael and gave her a promise that Ishmael would become ‘too numerous to count’. So with this encounter and promise she returned to her mistress and the rivalry paused.
The Rivalry Grows
But when Isaac was born to Sarai 14 years later the rivalry started again. We read in the Taurat how this happened.
8 The child [i.e. Isaac] 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.”
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 the 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.
We see that Sarah (her name had been changed from Sarai) could not live in the same household with Hagar and demanded that she be sent away. Though Ibrahim (PBUH) was reluctant, Allah promised that he would bless Hagar and Ishmael (PBUH). Indeed He spoke to her again, opened her eyes to see water in the desert and promised that Ishmael (PBUH) would become a ‘great nation’.
The Taurat continues showing how this nation started in its development. We read about Ishmael (PBUH) at the time of the death of Ibrahim (PBUH).
8 Then Abraham breathed his last and died at a good old age, an old man and full of years; and he was gathered to his people. 9 His sons Isaac and Ishmael buried him in the cave of Machpelah near Mamre, in the field of Ephron son of Zohar the Hittite, 10 the field Abraham had bought from the Hittites. There Abraham was buried with his wife Sarah. 11 After Abraham’s death, God blessed his son Isaac, who then lived near Beer Lahai Roi.
12 This is the account of the family line of Abraham’s son Ishmael, whom Sarah’s slave, Hagar the Egyptian, bore to Abraham.
13 These are the names of the sons of Ishmael, listed in the order of their birth: Nebaioth the firstborn of Ishmael, Kedar, Adbeel, Mibsam, 14 Mishma, Dumah, Massa, 15 Hadad, Tema, Jetur, Naphish and Kedemah. 16 These were the sons of Ishmael, and these are the names of the twelve tribal rulers according to their settlements and camps. 17 Ishmael lived a hundred and thirty-seven years. He breathed his last and died, and he was gathered to his people. 18 His descendants settled in the area from Havilah to Shur, near the eastern border of Egypt, as you go toward Ashur. And they lived in hostility toward all the tribes related to them.
Ishmael lived a very long time indeed and that his sons became 12 tribal rulers. Allah had blessed him as He had promised. Arabs to this day trace their ancestry to Ibrahim through Ishmael.