John Wesley on 2 Chronicles 20:22

To sing - So acceptable are the fervent prayers of God's people to God, and so terrible to their enemies. Ambushments - Or, liers in wait, either the holy angels, who appeared in the shape of men, and possibly put on the appearances and visages of the Moabites or Ammonites, and in that shape slew the rest, who supposing this slaughter to be done by a part of their own army, fell upon them, and so broke forth into mutual slaughters. Or, God raised jealousies and animosities among themselves, which broke forth, first into secret ambushments, which one party laid for another, and then into open hostilities to their utter destruction. So vain are all mens attempts against God, who needs none to destroy his enemies but themselves, and their own mistakes, and passions, which he can, when he pleaseth, arm against them.