Genesis 21:9 And Sarah saw the son of Hagar the Egyptian, which she had born unto Abraham, mocking. 10 Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac.
[Patriarchs & Prophets pp 146>147] 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 patriarch was thrown into great distress. How could he banish Ishmael his son, still dearly beloved? In his perplexity he pleaded for divine guidance. The Lord, through a holy angel, directed him to grant Sarah's desire; his love for Ishmael or Hagar ought not to stand in the way, for only thus could he restore harmony and happiness to his family.
And the angel gave him the consoling promise that though separated from his father's home, Ishmael should not be forsaken by God; his life should be preserved, and he should become the father of a great nation. Abraham obeyed the angel's word, but it was not without keen suffering. The father's heart was heavy with unspoken grief as he sent away Hagar and his son. The instruction given to Abraham touching the sacredness of the marriage relation was to be a lesson for all ages. It declares that the rights and happiness of this relation are to be carefully guarded, even at a great sacrifice. Sarah was the only true wife of Abraham. Her rights as a wife and mother no other person was entitled to share.
She reverenced her husband, and in this she is presented in the New Testament as a worthy example. But she was unwilling that Abraham's affections should be given to another, and the Lord did not reprove her for requiring the banishment of her rival. Both Abraham and Sarah distrusted the power of God, and it was this error that led to the marriage with Hagar. od had called Abraham to be the father of the faithful, and his life was to stand as an example of faith to succeeding generations. But his faith had not been perfect. He had shown distrust of God in concealing the fact that Sarah was his wife, and again in his marriage with Hagar.
1st Corinthians 7:2 Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband.
May God add His blessing to the study of His word. "Good night" and God bless!