With a fixed heart, a heart devoted to that purpose, we can sing and give praise to God. What does it mean, “even with my glory.” I am not sure. Matthew Henry gives an idea, “David's skill in music was his glory, it made him famous, and this should be consecrated to the praise of God; and therefore it follows, Awake my psaltery and harp. Whatever gift we excel in we must praise God with.” Any skill we have or any influence we may have is a gift from God and should be used to praise Him.
Who should hear our songs and praises to God? Verse three answers that question, “I will praise thee, O LORD, among the people: and I will sing praises unto thee among the nations.” Everyone should hear it, especially the lost. Everyone should know we have a God worthy of song and praise.
Why is God worthy of my song and praise? “Thy mercy is great above the heavens: and thy truth reacheth unto the clouds.” (verse 4) God is worthy of song and praise because of His great mercy and because of His truth, which is so great, that no other thought or ideology can rise above it. “Be thou exalted, O God, above the heavens: and thy glory above all the earth.”