Genesis 30:12

And when Rachel saw that she bare Jacob no children, Rachel envied her sister; and said unto Jacob, Give me children, or else I die.

And Jacob's anger was kindled against Rachel: and he said, Am I in God's stead, who hath withheld from thee the fruit of the womb?

And she said, Behold my maid Bilhah, go in unto her; and she shall bear upon my knees, that I may also have children by her.

And she gave him Bilhah her handmaid to wife: and Jacob went in unto her.