thirty and seventh. Joash (of Israel) became king in the thirtyseventh year of Joash (of Judah). Amaziah, son of Joash (of Judah), became king in the second year of Joash (of Israel), 2 Kings 14:1. Therefore Amaziah became associate king in the thirty-ninth year of Joash of Judah: i.e. one year before Joash died, for he "reigned forty years in Jerusalem" (1 Chronicles 24:1). The cause of Amaziah's kingship in Joash's lifetime is not named in Kings, but we see it in the "diseases" of 2 Chronicles 24:25.
over: i.e. in consort with his father. Compare 2 Kings 14:1.