When Israel dwelt there, Reuben [his eldest son] went and lay with Bilhah his father's concubine; and Israel heard about it. Now Jacob's sons were twelve.
The sons of Judah: Er, Onan, and Shelah, whom Shua's daughter the Canaanitess bore him. Er, Judah's eldest, was evil in the Lord's sight, and He slew him.