John Gill Commentary 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 20:18 (ASV)

And Jehoshaphat bowed his head with his face to the ground ,
&c.] Not only in reverence of God, and his prophet, but as a token of his belief of what was said, and his thankfulness for it: and all Judah, and the inhabitants of Jerusalem, fell before the Lord,
worshipping him ;
adoring his goodness to them, in imitation of their king.