You will not need to fight in this battle. Stand firm, hold your position, and see the salvation of the LORD on your behalf, O Judah and Jerusalem.’ Do not be afraid and do not be dismayed. Tomorrow go out against them, and the LORD will be with you.”
We have here God's gracious answer to Jehoshaphat's prayer; and it was a speedy answer. While he was yet speaking God heard: before the congregation was dismissed they had assurance given them that they should be victorious; for it is never in vain to seek God. 1.
Commenting on 2 Chronicles 20:14-19
Ye shall not need to fight in this battle,.... Since the Lord would fight for them: set yourselves, stand ye still; present themselves they might, as if ready to engage; and keep their ground, not giving way in the least, but would have no need to strike a stroke: and see the salvation of the Lord with you; which he would work for them, see...
For the Lord will be with you - "The Word of the Lord shall be your Helper." - Targum.