The book of Psalms includes a number of psalms called hallelujah or praise psalms. These psalms are songs of praise that would have been sung by the Jews as they magnified God, praising His name, His acts, and His wonderful attributes. A hallelujah psalm has three parts. The first part of the psalm is the introduction, or call to praise. The introduction is followed by the development part of the psalm, which lists the reasons to praise God. The last part of the psalm, the conclusion, is often a prayer or an exhortation.
The last five psalms found in the book of Psalms are considered the Hallel of Hallelujah Psalms. Each one of these psalms begins with a call to praise, hallelujah, which is the Hebrew word for "praise the Lord." These five psalms are also unique among the hallelujah psalms in that the development part of the psalms, rather than listing the reasons to praise God, repeat the command to praise God.
In one of these psalms, Psalm 149, the psalmist, likely David, was giving praise for God's love for Israel. The psalm begins with the call to praise, "Praise the Lord," then says to sing a new song to the Lord. The new song might mean singing a song to the Lord that has never been sung before, but it could also mean singing a familiar song with a fresh heart, singing it as if you've never sung it before, giving it a new freshness.
The psalm then continues by giving the command to rejoice in God and be glad in Him. The faithful are encouraged, not just to sing their praise to God, but also to praise Him with dancing and musical instruments (Psalm 149:2-3). As you read this psalm, it is easy to imagine the excitement of the Jews as they lifted these praises to the Lord. As they sang this beautiful song of praise, they were clapping their hands and dancing as they sang and celebrated God's faithfulness, love, and mercy. We should have that same excitement as we offer praise to God.
Psalm 149 also shows praise as a powerful weapon of spiritual warfare (Psalm 149:6-9). With God's praises in their mouths and a double-edged sword, which is God's Word, in their hands, God's faithful people are able, not only to defeat the enemy, but to bind him in fetters. One day, when Jesus returns to reign on earth, all of God's faithful people will take part in the judgment of the enemy. When you think of this, it should make you want to shout, "Hallelujah!" And that is exactly how this psalm ends - "Praise the Lord!"