Genesis 30:3-5

Amplified Bible

³ She said, “Here, take my maid Bilhah and go in to her; and [when the baby comes] she shall ^[a]deliver it [while sitting] on my knees, so that by her I may also have children [to count as my own].” ⁴ So she gave him Bilhah her maid as a [^[b]secondary] wife, and Jacob went in to her. ⁵ Bilhah conceived and gave birth to a son for Jacob.