John Calvin Commentary Psalms 104:33

"I will sing unto Jehovah as long as I live: I will sing praise to my God while I have any being." — Psalms 104:33 (ASV)

I will sing to Jehovah while I live. Here the Psalmist points out to others their duty by his own example, declaring that throughout the whole course of his life he will proclaim the praises of God without ever growing weary of this practice. The only boundary he sets for celebrating God’s praises is death; not that the saints, when they pass from this world into another state of existence, cease this religious duty, but because the purpose for which we are created is that the divine name may be celebrated by us on the earth.

Conscious of his unworthiness to offer God so precious a sacrifice, he humbly prays (verse 34) that the praises he will sing to God may be acceptable to him, although they proceed from polluted lips. It is true that there is nothing more acceptable to God, nor anything he approves of more, than proclaiming his praises, just as there is no service he more particularly requires us to perform.

But since our uncleanness defiles what is inherently most holy, the prophet rightly turns to the goodness of God, and on this ground alone pleads that God would accept his song of praise. Accordingly, the Apostle, in Hebrews 13:15, teaches that our sacrifices of thanksgiving are well-pleasing to God when they are offered to him through Christ.

However, although all people indiscriminately enjoy God’s benefits, still very few look to their Author. The prophet therefore adds the clause, I will rejoice in the Lord, intimating that this is a rare virtue. For nothing is more difficult than to recall the mind from those wild and erratic joys, which scatter themselves through heaven and earth where they vanish, so that it may keep itself fixed on God alone.