She vowed a vow, and said, Yahweh of hosts, if you will indeed look on the affliction of your handmaid, and remember me, and not forget your handmaid, but will give to your handmaid a man-child, then I will give him to Yahweh all the days of his life, and there shall no razor come on his head.
So the scene is set the man living in polygamy, two wives. One he loved more than the other. One had many children, but the one he really loved could not have any children.