2 Chronicles 27:5

He fought also with the king of the Ammonites, and prevailed against them. And the children of Ammon gave him the same year an hundred talents of silver, and ten thousand measures of wheat, and ten thousand of barley. So much did the children of Ammon pay unto him, both the second year, and the third.

He fought also with the king of the Ammonites. This invasion he not only repelled, but, pursuing the Ammonites into their own territory, imposed on them a yearly tribute, which for two years they paid; but when Rezin, king of Syria, and Pekah, king of Israel, combined to attack the kingdom of Judah, they took the opportunity of revolting, and Jotham was too distracted by other matters to attempt the re-conquest (see the note at 2 Kings 15:37).