Genesis 16:4
And he went in unto Hagar, and she conceived: and when she saw that she had conceived, her mistress was despised in her eyes. And he went in unto Hagar, and she conceived: and when she saw that she had conceived, her mistress was despised in her eyes.
Abraham took Hagar at Sarah's suggestion because they distrusted God's power to fulfill the promise and would not wait for Him to fulfill it in His own time and way, and when he went in unto her she conceived by him. When Hagar saw that she had conceived she despised Sarah her mistress, becoming proud, boastful and haughty toward her and flattering herself that she would be the mother of the great nation promised to Abraham, thus becoming her rival. Taking Hagar was polygamy and a departure from God's order of one wife for one man established with Adam, which God never sanctioned because it was contrary to His will and would destroy man's happiness, while Sarah remained Abraham's first and only true wife entitled to the rights of wife and mother that no other could share. The act brought evil into Abraham's household in jealousy, unhappiness, sorrow, anguish and lasting division, showing that restless efforts to secure God's promises by human devising bring misery and sin rather than the outcome God intends. The harm reached beyond the household to later generations through Ishmael's birth in descendants who opposed God and His purposes.
Background and Hagar's Contempt
Abraham took Hagar at Sarah's suggestion because he and Sarah distrusted God's power to fulfill the promise and failed to wait for God to fulfill it in His own time and way, devising their own plan to bring it about. That lack of perfect trust in taking Hagar was the background of what followed. After Abraham went in unto Hagar, she conceived by him.
When Hagar saw that she had conceived, her mistress was despised in her eyes, and she looked with contempt on Sarah her mistress. Pride led her to look down on Sarah, and she became proud, boastful, and haughty toward her. She wrongly flattered herself that she would be the mother of the great nation promised to Abraham.
In conceiving, Hagar became Sarah's rival. Abraham's lack of trust in taking Hagar was later redeemed by his faithfulness in the test involving Isaac.
Household Harm and Marriage
The conception turned Abraham's household toward evil, filling it with jealousy and unhappiness and setting family relationships toward lasting division. That breach came because the promise was sought by a human device instead of waiting for God to fulfill it in His own time and way, and the restless attempt brought sorrow and anguish and misery and sin. Restless efforts to secure what God has promised by human means lead to misery rather than to the outcome God intends. The harm did not stop with the household but reached later generations through the birth of Ishmael, producing descendants who opposed God and His purposes.
Taking Hagar as an additional wife was polygamy and a departure from God's order of one wife for one man established with Adam. God never sanctioned polygamy in a single instance, because it was contrary to His will and He knew it would destroy man's happiness. It was no less sin for having become common after the Flood or for being practiced even by righteous men, and in Abraham's case it greatly marred his peace through the unhappy union. Sarah was Abraham's first and only true wife, entitled to the rights of a wife and mother which no other person was entitled to share. The episode shows the harm when those rights are not carefully guarded, and that polygamy does not honor the rights and happiness of the marriage relation.