21 After talking it over with the people, Jehoshaphat appointed a choir for God; dressed in holy robes, they were to march ahead of the troops, singing, Give thanks to God, His love never quits. 22 As soon as they started shouting and praising, God set ambushes against the men of Ammon, Moab, and Mount Seir as they were attacking Judah, and they all ended up dead. 23 The Ammonites and Moabites mistakenly attacked those from Mount Seir and massacred them. Then, further confused, they went at each other, and all ended up killed. 24 As Judah came up over the rise, looking into the wilderness for the horde of barbarians, they looked on a killing field of dead bodies - not a living soul among them.
Matthew Henry's Commentary on 2 Chronicles 20:21-24
Commentary on 2 Chronicles 20:20-30
(Read 2 Chronicles 20:20-30)
Jehoshaphat exhorted his troops to firm faith in God. Faith inspires a man with true courage; nor will any thing help more to the establishing of the heart in shaking times, than a firm belief of the power, and mercy, and promise of God. In all our trust in the Lord, and our praises of him, let us especially look at his everlasting mercy to sinners through Jesus Christ. Never was an army so destroyed as that of the enemy. Thus God often makes wicked people destroy one another. And never was a victory celebrated with more solemn thanksgivings.