Genesis 30:3

“And she said, etc.] in order to pacify Jacob, and explain her meaning to him; which was, not that she thought it was in his power to make her the mother of children, but that he would think of some way or another of obtaining children for her, that might go for hers; so the Arabic version, “obtain a son for me”: but, since no method occurred to him, she proposes one: behold my maid Bilhah, go in unto her, take her and use her as thy wife: and she shall bear upon my knees; either sit on her knees in the time of labour, and so bring forth as if it was she herself; or rather bear a child, which Rachel would take and nurse, and dandle upon her knees as her own, (see <236612>Isaiah 66:12); that I…”

“Bilhah . . . Zilpah--Following the example of Sarah with regard to Hagar, an example which is not seldom imitated still, she adopted the children of her maid. Leah took the same course. A bitter and intense rivalry existed between them, all the more from their close relationship as sisters; and although they occupied separate apartments, with their families, as is the uniform custom where a plurality of wives obtains, and the husband and father spends a day with each in regular succession, that did not allay their mutual jealousies. The evil lies in the system, which being a violation of God's original ordinance, cannot yield happiness.”

“30:3-4 Rachel’s decision to have children through her servant, and Jacob’s compliance, recall Sarai’s use of Hagar (16:1-4).”