Genesis 35:22-26

And it happened, when Israel dwelt in that land, that Reuben went and lay with Bilhah his father’s concubine; and Israel heard about it. Now the sons of Jacob were twelve: the sons of Leah were Reuben, Jacob’s firstborn, and Simeon, Levi, Judah, Issachar, and Zebulun; the sons of Rachel were Joseph and Benjamin; the sons of Bilhah, Rachel’s maidservant, were Dan and Naphtali; and the sons of Zilpah, Leah’s maidservant, were Gad and Asher. These were the sons of Jacob who were born to him in Padan Aram.