Divrey Hayamim Bais 20:15

15 And he said, Pay heed ye, all Yehudah, and ye inhabitants of Yerushalayim, and thou Melech Yehoshaphat. Thus saith Hashem unto you: Be not afraid nor dismayed by reason of this great multitude; for the milchamah is not yours, but that of Elohim.

Divrey Hayamim Bais 20:15 Meaning and Commentary

2 Chronicles 20:15

And he said, hearken ye, all Judah, and ye inhabitants of
Jerusalem, and thou King Jehoshaphat
There is a climax or gradation in these words rising from the lowest to the highest; from the people of the cities in the country, to the inhabitants of Jerusalem the metropolis, and from thence to the king the supreme governor: thus saith the Lord unto you, be not afraid, nor dismayed, by reason of
this great multitude;
whose numbers were discouraging to the king, and he had taken notice of them, which this respects: for the battle is not your's, but God's:
the cause was his, and he would espouse and maintain it; not they, but he, would fight the battle, and therefore they had nothing to fear.

Divrey Hayamim Bais 20:15 In-Context

13 And all Yehudah stood before Hashem, with their little ones, their nashim, and their banim.

14 Then upon Yachziel ben Zecharyahu ben Benayah ben Ye’i’el ben Matanyah, a Levi of the Bnei Asaph, came the Ruach Hashem in the midst of the Kahal,

15 And he said, Pay heed ye, all Yehudah, and ye inhabitants of Yerushalayim, and thou Melech Yehoshaphat. Thus saith Hashem unto you: Be not afraid nor dismayed by reason of this great multitude; for the milchamah is not yours, but that of Elohim.

16 Makhar (tomorrow) go ye down against them; hinei, they come up by the Ascent of Tzitz; and ye shall find them at the end of the wadi, before the midbar of Yeruel.

17 Ye shall not need to fight in this; take up your battle positions, stand ye firm, and see the Yeshuat Hashem with you, O Yehudah and Yerushalayim. Fear not, nor be dismayed; makhar (tomorrow) go out against them, for Hashem will be with you.