Charles Ellicott Commentary 1 Chronicles 2:3

"The sons of Judah: Er, and Onan, and Shelah; which three were born unto him of Shua`s daughter the Canaanitess. And Er, Judah`s first-born, was wicked in the sight of Jehovah; and he slew him." — 1 Chronicles 2:3 (ASV)

THE FIVE SONS OF JUDAH, FROM Genesis 38 .

The daughter of Shua the Canaanitess. —Shua was the father of Judah’s wife.

Er, the firstborn of Judah, was (became, proved) evil. —Word for word from Genesis 38:7. Suppressing other details relating to the sons of Judah, the chronicler copies this statement intact from Genesis, because it thoroughly harmonizes with the moral he wishes to be drawn from the entire history of his people.