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. Abraham's marriage with Hagar resulted in evil, not only to his own household, but to future generations.

Dette kapitel er bygget op over 1. mos 16; 17, 18-20; 21, 1-14; 22, 1-19
Abraham havde uden at stille spørgsmål modtaget løftet om en søn, men han ventede ikke, til Gud opfyldte sit ord til sin tid og på sin måde. Løftets opfyldelse blev udsat for at prøve hans tro på Guds magt; men han bestod ikke prøven. Da Sara mente, at det var umuligt, at hun kunne få en søn i sin alderdom, foreslog hun, at Abraham skulle tage en af hendes tjenestepiger som medhustru, for at Guds hensigt kunne opfyldes. Flerkoneri var blevet så udbredt, at det ikke mere regnedes for synd; men det var alligevel en overtrædelse af Guds lov og var skæbnesvangert for familielivets hellighed og fred. Abrahams ægteskab med Hagar fik onde følger, ikke alene for hans egen husstand, men også for fremtidige slægter.