Genesis 16:2

a. And Sarai said unto Abram, Behold now, the Lord hath constrained me from bearing; I pray thee, go in unto my maid; it may be that I may obtain children by her. The fact of Sarai's barrenness had been mentioned at the time of their coming to Canaan, Genesis 11:30. It is repeated here for the sake of the emphasis upon the miracle which the Lord wrought in her case. Ten years had now passed by, and yet, in spite of the promise, Genesis 15:4, Sarai remained without a child. She therefore be came impatient and suggested to Abram that, since the Lord hindered her from bearing, denied her offspring, her Egyptian slave Hagar might be the one through whom she was to have children, that her family might be built up through the slave. According to the custom of the Orient the children of slaves belonged to the master and mistress, Exodus 21:4; 1 Chronicles 2:35.

b. And Abram hearkened to the voice of Sarai.