What happened to Ishmael in the Bible?

At the "great feast" when Isaac, the child born after the Spirit, was weaned, Ishmael mocked, and Sarah begged Abraham to cast out both mother and son. This was painful to Abraham, but God approved what she said, so he rose early in the morning, gave them some bread and a bottle of water, and sent them away. The water was soon used up, and Hagar in despair placed Ishmael under a shrub and walked away so as not to see him die. The angel of God called to her, showed her a well, and the child was saved. God was with the boy, for he was Abraham's offspring; he lived in the wilderness and became an archer... His twelve sons are recorded... Ishmael was present at the burial of his father and lived 137 years.

Abraham's heart longed over Ishmael. His cry was, "Oh that Ishmael might live before You!" And more than that, Ishmael was circumcised, so the mark of the covenant was outwardly put on him... It had been said of Ishmael that he would be a wild man, his hand against every man and every man's hand against him. He remained a wild, stubborn, quarrelsome fellow — a fitting picture of the flesh... Ishmael's time of testing ended, however, when he proved himself not only wild but a scorner and a mocker toward the promised offspring, Isaac.

Ishmael was by now old enough to understand that it was God's will for his brother Isaac to hold a more honoured position than he himself could hold. Isaac, the young Isaac, was chosen by God to be Abraham's heir. If Ishmael had quietly accepted this, the will of God, and honoured his younger brother Isaac, he would no doubt have been allowed to stay in his father's house. But he did not bow to God's will.

Abraham found this extremely hard to do, because after all Ishmael was actually his son (v. 11). So God Himself stepped in to tell him not to be grieved in acting on Sarah's word. However he felt about it, his feelings were not to rule in this matter... In fact, when Galatians 4:30 refers to this, Sarah's words are called "scripture": "But what does the Scripture say? 'Cast out the slave woman and her son.'" In other words, it was God who put those words in Sarah's mouth.

Turning again to his allegory, the Apostle says that believers now are like Isaac, the children of promise. But as it was on the day when Isaac was weaned, Ishmael mocked, so now the one born according to the flesh and under bondage of law will persecute the one born after the Spirit and in the liberty of grace. The flesh and the Spirit are always opposed. It was so in Abraham's house, it is so in the world, and even in the heart of the believer.

When the mother gave in to despair and laid her son down to die some distance from her, "God heard the voice of the boy," and His angel tells Hagar to hold him by the hand. Had not the LORD called his name Ishmael, because He had heard her affliction?... God opened her eyes to see a well of water, and she gave the boy a drink. If she forgot the divine promise... God remembered him and declares that He will make him a great nation.

And what of the boy? He too clearly lifted up his voice — not to weep, but to pray... you remember that his name means "Heard of God"... Ishmael very likely was jealous of the little boy who had become "heir of all things" instead of himself... Remembering these things, it is especially pleasing to find Ishmael together with Isaac burying his father. Surely we may see that God was working in his heart.

Ishmael speaks of our condition by nature, when the flesh has undisputed possession and we live to please self... It was not an improved Ishmael that was to hold God's promises, but Isaac, the new man... Ishmael might become "a great nation," the father of twelve princes, but he was still the son of the slave woman.