After this the Moabites and Ammonites, and with them some of the Meunites, came against Jehoshaphat for battle. Messengers came and told Jehoshaphat, “A great multitude is coming against you from Edom, from beyond the sea; already they are at Hazazon-tamar” (that is, En-gedi). Jehoshaphat was afraid; he set himself to seek the Lord and proclaimed a fast throughout all Judah. Judah assembled to seek help from the Lord; from all the towns of Judah they came to seek the Lord.
Jehoshaphat stood in the assembly of Judah and Jerusalem, in the house of the Lord, before the new court, and said, “O Lord, God of our ancestors, are you not God in heaven? Do you not rule over all the kingdoms of the nations? In your hand are power and might, so that no one is able to withstand you. Did you not, O our God, drive out the inhabitants of this land before your people Israel and give it forever to the descendants of your friend Abraham? They have lived in it and in it have built you a sanctuary for your name, saying, ‘If disaster comes upon us, the sword, judgment, or pestilence, or famine, we will stand before this house and before you, for your name is in this house, and cry to you in our distress, and you will hear and save.’ See now, the people of Ammon, Moab, and Mount Seir, whom you would not let Israel invade when they came from the land of Egypt and whom they avoided and did not destroy, they reward us by coming to drive us out of your possession that you have given us to inherit. O our God, will you not execute judgment upon them? For we are powerless against this great multitude that is coming against us. We do not know what to do, but our eyes are on you.”
Meanwhile, all Judah stood before the Lord, with their little ones, their wives, and their children. Then the spirit of the Lord came upon Jahaziel son of Zechariah, son of Benaiah, son of Jeiel, son of Mattaniah, a Levite of the sons of Asaph, in the middle of the assembly. He said, “Listen, all Judah and inhabitants of Jerusalem and King Jehoshaphat: Thus says the Lord to you: Do not fear or be dismayed at this great multitude, for the battle is not yours but God’s. Tomorrow go down against them; they will come up by the ascent of Ziz; you will find them at the end of the valley, before the wilderness of Jeruel. This battle is not for you to fight; take your position, stand still, and see the victory of the Lord on your behalf, O Judah and Jerusalem. Do not fear or be dismayed; tomorrow go out against them, and the Lord will be with you.”
Then Jehoshaphat bowed down with his face to the ground, and all Judah and the inhabitants of Jerusalem fell down before the Lord, worshiping the Lord. And the Levites of the Kohathites and the Korahites stood up to praise the Lord, the God of Israel, with a very loud voice.
They rose early in the morning and went out into the wilderness of Tekoa, and as they went out Jehoshaphat stood and said, “Listen to me, O Judah and inhabitants of Jerusalem! Believe in the Lord your God and you will be established; believe his prophets and you will succeed.” When he had taken counsel with the people, he appointed those who were to sing to the Lord and praise him in holy splendor, as they went before the army, saying,
“Give thanks to the Lord, for his steadfast love endures forever.”
As they began to sing and praise, the Lord set an ambush against the Ammonites, Moab, and Mount Seir who had come against Judah, so that they were routed. For the Ammonites and Moab attacked the inhabitants of Mount Seir, destroying them utterly, and when they had made an end of the inhabitants of Seir, they all helped to destroy one another.
When Judah came to the watchtower of the wilderness, they looked toward the multitude; they were corpses lying on the ground; no one had escaped. When Jehoshaphat and his people came to take the spoil from them, they found livestock in great numbers, goods, clothing, and precious things, which they took for themselves until they could carry no more. They spent three days taking the spoil because of its abundance. On the fourth day they assembled in the Valley of Beracah, for there they blessed the Lord; therefore that place has been called the Valley of Beracah to this day. Then all the people of Judah and Jerusalem, with Jehoshaphat at their head, returned to Jerusalem with joy, for the Lord had enabled them to rejoice over their enemies. They came to Jerusalem with harps and lyres and trumpets to the house of the Lord. The fear of God came on all the kingdoms of the countries when they heard that the Lord had fought against the enemies of Israel. And the realm of Jehoshaphat was quiet, for his God gave him rest all around.
So Jehoshaphat reigned over Judah. He was thirty-five years old when he began to reign; he reigned twenty-five years in Jerusalem. His mother’s name was Azubah daughter of Shilhi. He walked in the way of his father Asa and did not turn aside from it, doing what was right in the sight of the Lord. Yet the high places were not removed; the people had not yet set their hearts upon the God of their ancestors.
Now the rest of the acts of Jehoshaphat, from first to last, are written in the Annals of Jehu son of Hanani, which are recorded in the Book of the Kings of Israel.
After this King Jehoshaphat of Judah joined with King Ahaziah of Israel, who did wickedly. He joined him in building ships to go to Tarshish; they built the ships in Ezion-geber. Then Eliezer son of Dodavahu of Mareshah prophesied against Jehoshaphat, saying, “Because you have joined with Ahaziah, the Lord will destroy what you have made.” And the ships were wrecked and were not able to go to Tarshish.
Resource: 2 Chronicles 20, New Revised Standard Version Updated Edition (NRSVUE), Bible Gateway