Abraham had accepted without question the promise of a son, but he did not wait for God to fulfill His word in His own time and way. A delay was permitted, to test his faith in the power of God; but he failed to endure the trial. Thinking it impossible that a child should be given her in her old age, Sarah suggested, as a plan by which the divine purpose might be fulfilled, that one of her handmaidens should be taken by Abraham as a secondary wife. Polygamy had become so widespread that it had ceased to be regarded as a sin, but it was no less a violation of the law of God, and was fatal to the sacredness and peace of the family relation....
Though it was at Sarah's earnest entreaty that he had married Hagar, she now reproached him as the one at fault. She desired to banish her rival; but Abraham refused to permit this; for Hagar was to be the mother of his child, as he fondly hoped, the son of promise.... “When Sarai dealt hardly with her, she fled from her face.”
She made her way to the desert, and as she rested beside a fountain, lonely and friendless, an angel of the Lord, in human form, appeared to her.... He bade her, “Return to thy mistress, and submit thyself under her hands.” ... As a perpetual reminder of His mercy, she was bidden to call her child Ishmael, “God shall hear.”
When Abraham was nearly one hundred years old, the promise of a son was repeated to him, with the assurance that the future heir should be the child of Sarah. But Abraham did not yet understand the promise....
The birth of Isaac, bringing, after a lifelong waiting, the fulfillment of their dearest hopes, filled the tents of Abraham and Sarah with gladness. But to Hagar this event was the overthrow of her fondly cherished ambitions. Ishmael, now a youth, had been regarded by all in the encampment as the heir of Abraham's wealth and the inheritor of the blessings promised to his descendants. Now he was suddenly set aside; and in their disappointment, mother and son hated the child of Sarah....
The general rejoicing increased their jealousy, until Ishmael dared openly to mock the heir of God's promise. Sarah saw in Ishmael's turbulent disposition a perpetual source of discord, and she appealed to Abraham, urging that Hagar and Ishmael be sent away from the encampment....
The instruction given to Abraham touching the sacredness of the marriage relation was to be a lesson for all ages.—Patriarchs and Prophets, 145-147. CTr 82
The effects of a flesh diet may not be immediately realized; but this is no evidence that it is not harmful. Few can be made to believe that it is the meat they have eaten which has poisoned their blood and caused their suffering. Many die of diseases wholly due to meat eating, while the real cause is not suspected by themselves or by others. MH 315
And Abraham ... took bread, and a bottle of water, and gave it unto Hagar, putting it on her shoulder, and the child, and sent her away. Genesis 21:14, KJV