On the fourth day they assembled in the Valley of Beracah, where they blessed the LORD. Therefore that place is called the Valley of Beracah to this day.
We have here the foregoing prayer answered and the foregoing promise performed, in the total overthrow of the enemies' forces and the triumph (for so it was rather than a victory) of Jehoshaphat's forces over them. I. Never was army drawn out to the field of battle as Jehoshaphat's was.
Commenting on 2 Chronicles 20:20-30
And on the fourth day they assembled themselves in the valley of Berachah,.... As it was afterwards called from what they did there, as follows, which was the reason of its name: for there they blessed the Lord; returned thanks to him for this wonderful appearance on their behalf, and gave him the glory of it; no doubt but they had given him praise before...
And on the fourth day they assembled themselves in the valley of Berachah; for there they blessed the LORD: therefore the name of the same place was called, The valley of Berachah, unto this day. (q) To give thanks to the Lord for the victory: and therefore the valley was called Berachah, that is, blessing or thanksgiving, which was also called the valley of Jehoshaphat...