2 Chronicles 13:7 Commentary - English Annotations on the Holy Bible by Matthew Poole

The children of Belial; such as have cast off the yoke and obedience which they owed both to God and to their king.

When Rehoboam was young; not in age, for he was then forty-one years old, but in his kingdom, which he had but newly obtained, and in experience in politic, and especially in military, affairs, to which he was wholly a stranger, as having been born and bred up in a time of great peace and security.

Tender-hearted, i.e. cowardly and fearful, who durst not adventure to chastise the rebels as he should have done. But therein Abijah forgets his duty, both to his father, whom he falsely traduceth; and to God, by whose express command Rehoboam was restrained from the war against Israel, which otherwise he had both courage and resolution to prosecute, as appears from the history, 1Ki 12:21.