Genesis 30:10 - John Gill's Exposition of the Entire Bible

And Zilpah, Leah's maid, bore Jacob a son. For it seems he consented to take her to wife at the motion of Leah, as he had took Bilhah at the instance of Rachel; and having gratified the one, he could not well deny the other; and went in to her, and she conceived, though neither of these things are mentioned, but are all necessarily supposed.