This is a psalm of David. He praises God and uses various terms to describe Him as a protector – his “rock”, “refuge”, “fortress”, “shield”. Similar to other psalms, David asks for deliverance from his enemies and exclaims that he will “sing a new song” to God for this rescuing.
Spurgeon comments on verse 9:
David intended to tune his best instruments as well as to use his best vocal music: the best is all too poor for so great a God, and therefore we must not fall short of our utmost.
David also reminds us that “Man is like a breath; his days are like a passing shadow.” (v. 4) – similar to warnings in the book of James and Psalm 90 (Moses) that ask us to number our days.
Heavenly Father, you are our rock and shield. Keep us from the laziness that sets in and the feeling that we have all the time in the world to accomplish Your work, as our days are but a passing shadow. Like your servant David, we will sing to you new songs and praise Your works. To You alone be the glory !