The Song of the Lamb

When Jehoshaphat, King of Judah, was outnumbered on the battlefield, he prayed to the Lord for help, and the Lord answered him through Jahaziel, son of Zechariah (2 Chron. 20).

You need not fight in this battle;
Station yourselves, stand and see the salvation of the Lord on your behalf, O Judah and Jerusalem.’
Do not fear or be dismayed;
Tomorrow go out to face them, for the Lord is with you.”

2 Chronicles 20:17

In response, the king bowed with his face to the ground, together with all of Judah. And on that night before battle, the Levites stood up and praised the Lord with a loud voice (see Matt. 26:30).

On the next day, they rose early in the morning (Matt. 27:1) and went out to the wilderness of Tekoa (v. 20). There, the text tells us, as they turned their faces towards the battle, Jehoshaphat put not soldiers but singers before their enemies (2 Chron. 20:20-23).

He appointed those who sang to the Lord and those who praised Him in holy attire, as they went out before the army and said,
“Give thanks to the Lord, for His lovingkindness is everlasting” (v. 21).

And when these holy singers began singing and praising, the Lord turned Judah’s songless enemies against one another, and “they helped to destroy one another” til no one escaped.

Victory completed, God’s enemy defeated, the people of Judah went down to collect the spoil. There was so much, God tells us, that they were three days taking the spoil, more than they could carry (Luke 24:5-7). So weighed down with God’s abundant gifts, on the fourth day, Judah assembled and named that place Valley of Beracah, “Valley of Blessings.” And they returned to Jerusalem with joy, carrying harps, lyres and trumpets.

And the dread of God was on all the kingdoms of the lands when they heard that the Lord had fought against the enemies of Israel. 
So the kingdom of Jehoshaphat was at peace, for his God gave him rest on all sides.

2 Chronicles 20:29-30

When God created the world, the angels sang over what He had made (Job 38:7). God Himself rejoices over us with singing (Heb. 2:11-13). Made in His image, by His loving Hand, we return to Him His Song of Songs (James 5:13).

And as we sing, we stand still and see the salvation of God over Satan and his demons. We see His power over the evil one, from whom He withholds the gift of singing. And these enemies we have seen, we will never see them again forever (Ex 14:13-14). For the Lord our God is in our midst. The Mighty One will save. He will quiet us with His love (Zeph. 3:17). He will carry us in peace through the valley of this world, to the New Jerusalem, City of God.

And I saw something like a sea of glass mixed with fire, and those who had been victorious over the beast and his image and the number of his name, standing on the sea of glass, holding harps of God. 
And they sang the song of Moses, the bond-servant of God, and the song of the Lamb, saying,

“Great and marvelous are Your works,
O Lord God, the Almighty;
Righteous and true are Your ways,
King of the nations!
“Who will not fear, O Lord, and glorify Your name?
For You alone are holy;
For all the nations will come and worship before You,
For Your righteous acts have been revealed.”
Revelations 15:2-4