Passage
Ye shall not have to fight on this occasion: set yourselves, stand and see the salvation of Jehovah [who is] with you! Judah and Jerusalem, fear not nor be dismayed; to-morrow go out against them, and Jehovah will be with you.
Ye shall not have to fight on this occasion: set yourselves, stand and see the salvation of Jehovah [who is] with you! Judah and Jerusalem, fear not nor be dismayed; to-morrow go out against them, and Jehovah will be with you.
2 Chronicles 20:15 and he said, Be attentive, all Judah, and ye inhabitants of Jerusalem, and thou king Jehoshaphat! Thus saith Jehovah unto you: Fear not, nor be dismayed by reason of this great multitude; for the battle is not yours, but God's.
2 Chronicles 20:16 To-morrow go down against them: behold, they come up by the ascent of Ziz; and ye shall find them at the end of the valley, before the wilderness of Jeruel.
2 Chronicles 20:17 Ye shall not have to fight on this occasion: set yourselves, stand and see the salvation of Jehovah [who is] with you! Judah and Jerusalem, fear not nor be dismayed; to-morrow go out against them, and Jehovah will be with you.
2 Chronicles 20:18 And Jehoshaphat bowed his head with his face to the ground; and all Judah and the inhabitants of Jerusalem fell down before Jehovah, worshipping Jehovah.
2 Chronicles 20:19 And the Levites, of the sons of the Kohathites, and of the sons of the Korahites, stood up to praise Jehovah the God of Israel with an exceeding loud voice.
The verse centers on "shall", "fight", "occasion", "yourselves", "stand", "salvation", "jehovah", and "judah". It is saying that the verse draws attention to "shall" and "fight", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 16's "To-morrow go down against them behold they..." into verse 18's "And Jehoshaphat bowed his head with his...", so "shall" and "fight" belong inside that flow. In 2 Chronicles context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "shall" and "fight" with trust shaped by these words, not by a vague optimism outside the passage.