Genesis 35:22-26

And it came about, while Israel was living in that land, that Reuben went and slept with his father’s concubine Bilhah, and Israel heard about it. Now there were twelve sons of Jacob—

the sons of Leah were Reuben, Jacob’s firstborn, then Simeon, Levi, Judah, Issachar, and Zebulun;

the sons of Rachel were Joseph and Benjamin;

and the sons of Bilhah, Rachel’s female slave, were Dan and Naphtali;

and the sons of Zilpah, Leah’s female slave, were Gad and Asher. These were the sons of Jacob who were born to him in Paddan-aram.