Verses 12-21:
Verses 12, 13: God (Elohim) spoke to Abraham to give him guidance in the matter of Ishmael and Hagar. Use of the term "bondwoman" with reference to Hagar indicates that God did not recognize her as Abraham’s wife (see Ge 16:8). In this vision, God instructs Abraham to heed the counsel of his wife Sarah. Abraham had listened to her on a previous occasion (Ge 16:2), and this had led him into a troublesome situation. The difference in the two occasions: in the matter of taking Hagar as a secondary wife, Sarah followed her own reasoning; in the matter of expelling Hagar and Ishmael, she followed the counsel and will of God. God reconfirmed His choice of Isaac, not Ishmael, as the promised seed.
God repeated a promise made earlier (Ge 17:20) concerning Ishmael. He would not be left utterly destitute, and die a pauper. Because of his relationship to Abraham, Ishmael would be the father of a great nation in his own right.
Verse 14-21: The next morning, Abraham sent Hagar and Ishmael away. The language implies that they started in the direction of Egypt. They did not at this time reach their destination.
Abraham supplied a bottle (skin) of water, and bread for the journey. After the custom of Egyptian women, Hagar took these supplies on her shoulder and set out on her journey with Ishmael as her companion - not carrying him literally but leading him by hand or arm. "Wilderness of Beer-sheba," the uncultivated wasteland between Palestine and Egypt. Soon the water supply was exhausted, and the two travelers became exhausted and in danger of fainting for thirst.
Hagar "cast the child under one of the shrubs." This translation conveys the erroneous impression that Ishmael was an infant, and that Hagar threw him violently to the ground under a bush. However, Ishmael was in his mid-teens, not an infant. The language indicates that Hagar supported his steps as long as she could. But she became exhausted and let him droop underneath a "shrub" siach (Sept. elates) or fir tree. Hagar then went about a "bowshot" from the fallen lad, and collapsed and began to weep in utter despair."
God (Elohim) heard Hagar’s weeping, and the piteous cries of Ishmael, and came to the rescue. He encouraged Hagar with the promise that Ishmael would live to become the father of a great nation. God showed Hagar a nearby well, a fountain or spring of living water. She replenished their supply, revived Ishmael, and went on the way. God exercised a special providence over Ishmael. He grew to manhood, living a roving, unsettled life, and acquired skill as a bowman. The "wilderness of Paran" (desert of El-Tih) became Ishmael’s home. Hagar secured a wife for him, from Egypt (see Ge 24:4, 55; Ex 21:10).