Count them and the number is almost comic. In six short verses some form of the word "praise" appears thirteen times. The psalm opens with it, closes with it, and cannot go three words in between without reaching for it again. It reads like a poem that has run out of anything else to say. This is what praise sounds like when it has stopped trying to explain itself and simply overflowed.
This is also the last psalm of the whole Psalter, and each of the five books that make up the collection ends with its own doxology (Psalm 41:13; 72:18-19; 89:52; 106:48). Psalm 150 is the grandest of those closings, placed deliberately as the last word over everything. What does that placement tell us? The reasons for all this praise are barely stated here, only in passing in verse 2, 2"for his mighty deeds; praise him according to his excellent greatness." The other hundred and forty-nine psalms already supplied the reasons, in overwhelming detail, long before this one arrived. After every lament, plea, confession, and long night of waiting, the Psalter reaches simple praise itself, finally free of any need to argue for anything.
Read the two clauses of verse 2 apart and do not read past them. Praise him for his mighty deeds is praise for what God has done. Praise him according to his excellent greatness is praise for who God simply is, apart from any deed at all. Together they guard against worship that only shows up when a fresh blessing has arrived. God is praiseworthy on the strength of his own being, whether or not this week has handed us a mighty deed to point to.
Then the list of instruments, and it carries liturgical weight. Trumpet, lute, harp, tambourine, dance, strings, pipe, cymbals covers every category used in Israel's worship, wind, string, and percussion, the whole orchestra called up at once. The ram's horn probably signaled the priests beginning the service, and the lyres went with the Levitical singers. The tambourine and dance almost certainly belonged to ordinary worshipers, women especially, as when Miriam and the women of Israel danced after the sea closed over Pharaoh's army (Exodus 15:20). Psalm 150 is remembering in poetry what the whole congregation sounded like when it gathered.
And the psalm keeps widening. It moves from 1"his sanctuary," the earthly temple where Israel gathered, to "his mighty heavens," the expanse no building could hold, so heaven and earth are praising together before the poem is half over. Then it stops naming instruments altogether, and the final verse draws the circle wider than even Israel's own worship usually dared to draw it. Whatever has been given breath by this God owes its breath back to him in praise, with no exceptions named and none implied.
That is where the Psalter's last word points straight at the New Testament's last words. John hears every creature in heaven and on earth and under the earth and in the sea singing to the Lamb (Revelation 5:13), and Paul says every knee will bow and every tongue confess that Jesus Christ is Lord (Philippians 2:10-11). What Psalm 150 gathers up as a hopeful, breathless summons, the New Testament shows happening, around a throne. The life the first psalm pictured as lived under God's instruction turns out to have had this as its end all along, unrestrained adoration.
Praise him today for a mighty deed, and then praise him for who he is, with no deed in view. Let both stay short and plain, and let the breath carry the rest.
Prayer
Father, we want the overflow this psalm cannot contain. We praise you for your mighty deeds toward us, and we praise you because you are who you are, whether or not this week has handed us fresh evidence of it. Let our worship, with whatever instrument or none, join the whole congregation that surrounds your throne, and let it widen past these walls to everything that has breath. In the name of Jesus, amen.