2 Chronicles 12:1

After Rehoboam had established his sovereignty and royal power, he and all Israel with him forsook the Law of the Lord.

Note That is, Judah; in 2 Chronicles, Judah is occasionally called Israel, as representative of the true Israel.

And it came to pass, when Rehoboam had established the kingdom, and had strengthened himself, he forsook the law of the Lord, and all Israel with him.

When the kingdom of Rehoboam was established and he was strong, he abandoned the Lord’s law, and all Israel with him.

And it came to pass, when the kingdom of Rehoboam was established, and he was strong, that he forsook the law of Jehovah, and all Israel with him.