This final psalm is a loud hymn of praise that closes the collection of five praise psalms that end Book V (Psalms 146-150), Book V itself, and the entire Psalter. It calls on "everything that breathes" to praise the Lord. Why? Because of God's "mighty deeds" (what God does) and God's "surpassing greatness" (who God is) (v. 2). Further detail is not spelled out, since the psalm assumes everything that is said about God in the 149 psalms that precede it. For all of that, let God be praised!
The psalm is loud, because everything on earth and in the heavens joins in praise (v. 1). Humans praise with voice and with instruments and with dance--finally with "loud clashing cymbals" (v. 5). The praise of God will be loud indeed, and properly so. We praise for who God is and what God does with all that we are and all that we do.
1 Praise the Lord!
Praise God in his sanctuary;
praise him in his mighty firmament!*
2 Praise him for his mighty deeds;
praise him according to his surpassing greatness!
3 Praise him with trumpet sound;
praise him with lute and harp!
4 Praise him with tambourine and dance;
praise him with strings and pipe!
5 Praise him with clanging cymbals;
praise him with loud clashing cymbals!
6 Let everything that breathes praise the Lord!
Praise the Lord!
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org