He had much business in the cities - He kept the people constantly employed; they had wages for their work; and by their labors the empire was both enriched and strengthened.

And he had much business in the cities of Judah,.... Partly in fortifying them, and partly in reforming the inhabitants of them:
and the men of war, mighty men of valour, were in Jerusalem; or by or near unto it, so the particle is rendered, Joshua 5:13, they encamped in places adjacent to it; for such a number of men as follows, even 1,160,000, could never be contained in Jerusalem, but must be disposed of in the territories of it; nor did they wait on the king together; but in course, see 2-Chronicles 17:19, by which it appears there is no need to suppose any mistake of the transcriber, in any or all of the following sums, as has been suggested (q).
(q) See Maitland's History of London, B. 3. ch. 2. p. 543.

וגו רבּה וּמלעכה is rightly translated by Luther, "und hatte viel Vorraths" (and had much store). מלעכה denotes here, as in Exodus 22:7-10, property, that which has been gained by work or business. The signification, much work, opera magna (Vulg., Cler., etc.), as also Bertheau's translation, "the works for equipping and provisioning the fortresses," correspond neither to the context nor to the parallel (synonymous) second member of the verse. The work and trouble necessary to equip the cities of Judah does not correspond to "the valiant warriors in Jerusalem;" the only parallel is the goods and property which were in these cities, the provision of victuals and war material there stored up.

Business - To repair and fortify them, and furnish them with provisions: and to purge out all their relicks of idolatry and injustice.