Matthew Henry on 2 Chronicles 20:1-13

In all dangers, public or personal, our first business should be to seek help from God. Hence the advantage of days for national fasting and prayer. From the first to the last of our seeking the Lord, we must approach him with humiliation for our sins, trusting only in his mercy and power. Jehoshaphat acknowledges the sovereign dominion of the Divine Providence. Lord, exert it on our behalf. Whom should we seek to, whom should we trust to for relief, but the God we have chosen and served. Those that use what they have for God, may comfortably hope he will secure it to them. Every true believer is a son of Abraham, a friend of God; with such the everlasting covenant is established, to such every promise belongs. We are assured of God's love, by his dwelling in human nature in the person of the Saviour. Jehoshaphat mentions the temple, as a token of God's favourable presence. He pleads the injustice of his enemies. We may well appeal to God against those that render us evil for good. Though he had a great army, he said, We have no might without thee; we rely upon thee.