Albert Barnes Commentary 2 Kings 14:28

"Now the rest of the acts of Jeroboam, and all that he did, and his might, how he warred, and how he recovered Damascus, and Hamath, [which had belonged] to Judah, for Israel, are they not written in the book of the chronicles of the kings of Israel?" — 2 Kings 14:28 (ASV)

He recovered Damascus - Jeroboam probably gained certain advantages over Benhadad, which induced the latter to submit and consent to terms like those extorted by Ahab (1 Kings 20:34).

Hamath was probably among the actual conquests of Jeroboam. It was brought so low in his reign that it became almost a byword for calamity .

Which belonged to Judah, for Israel - This means that these cities were recovered for Judah (that is, for the people of God generally) by being added to Israel (that is, to the northern kingdom).

A few more facts in the history of Jeroboam II are recorded by the prophet Amos (compare Amos 7:10 and following).