Charles Ellicott Commentary 2 Chronicles 20:17

"Ye shall not need to fight in this [battle]: set yourselves, stand ye still, and see the salvation of Jehovah with you, O Judah and Jerusalem; fear not, nor be dismayed: to-morrow go out against them: for Jehovah is with you." — 2 Chronicles 20:17 (ASV)

You shall not need to fight. — It is not for you to fight. (Compare to 1 Chronicles 5:1; 1 Chronicles 15:2.)

In this. — In this, in this instance. (Compare to 2 Chronicles 19:2 for the phrase.)

Set yourselves (that is, “withstand,” 2 Chronicles 20:6). — Station yourselves, take your stand. Here the next verb, stand you still, seems added as an explanation, and is, perhaps, a marginal gloss.

Fear not: take your stand, and see the salvation of the Lord, was the command of Moses to Israel at the Red Sea, just before the Great Deliverance (Exodus 14:13). (Compare also to the words of Psalm 46:8, Come, behold the works of the Lord, what desolations he hath made in the earth.)

The Lord with you. — Some explain the connection as follows: “The Lord (who is) with you.” Iahveh ‘immdkhem may, perhaps, be compared with ‘immânû êl, “with us God” (Isaiah 7:14; Isaiah 8:8); it will then be a Divine title, suited to the present emergency.

But, more probably, the stop should be at the Lord; and with you, O Judah and Jerusalem! is an elliptic expression, meaning “He is, or will be with you,” and so on, as in 2 Chronicles 19:6. (Compare to the refrain of Psalm 46:0, The Lord of hosts is with us! The God of Jacob is our refuge.)