Genesis 35:21-23

New Revised Standard Version, Anglicised

²¹ Israel journeyed on, and pitched his tent beyond the tower of Eder.

²² While Israel lived in that land, Reuben went and lay with Bilhah his father’s concubine; and Israel heard of it.

Now the sons of Jacob were twelve. ²³ The sons of Leah: Reuben (Jacob’s firstborn), Simeon, Levi, Judah, Issachar, and Zebulun.