Genesis 35:22-26

And it came to pass, while Israel dwelt in that land, that Reuben went and lay with Bilhah his father’s concubine: and Israel heard of it. Now the sons of Jacob were twelve: the sons of Leah: Reuben, Jacob’s first-born, and Simeon, and Levi, and Judah, and Issachar, and Zebulun; the sons of Rachel: Joseph and Benjamin; and the sons of Bilhah, Rachel’s handmaid: Dan and Naphtali; and the sons of Zilpah, Leah’s handmaid: Gad and Asher: these are the sons of Jacob, that were born to him in Paddan-aram.