Bible Notes Online - 2-Chronicles 17 - ESV
Commentary

v1-2: Jehoshaphat, following Asa's good example, delighted in the things of the Lord God. The main threat was from Israel, and he strengthened his northern-facing defences. We may find that 'nominal' Christians are a bigger threat to those of real faith, with their criticism, mocking and accusations.

v3: Jehoshaphat was like David, and he did not seek the Baals.

v4: He also avoided the practices that Israel had followed. He fulfilled God's standards, not the ways of man.

v5: As with previous kings, the Lord established the kingdom under Jehoshaphat.

v6: His heart was devoted to the Lord, in that he continued to remove those bad influences from the nation.

v7-9: Jehoshaphat had the people learn the law of God. Wisely he delegated this task to others, including Levites. This promoted personal godliness. Shared leadership also reduced the influence of any one individual.

v10-11: The powerful influence of a God-fearing nation. There is immense good when God's people know God's word and obey it.

v12-13: Jehoshaphat grew more powerful. He improved the defences of Judah, and provided storage cities.

v14-19: Jehoshaphat's army was 1,160,000, compared to Asa's 580,000 (14.8), and Abijah's 400,000 (13.3); this matches the blessing of God upon His people.

The Lord's army was proven, equipped, and willing; God's work demands godly attitudes; Eliada was already a "valiant soldier"; the men were "armed for battle"; and Amasiah "volunteered himself".