Praise the Lord with the harp, &c. He mentions these instruments, because they were used in the public worship of God in the tabernacle. Sing unto him a new song Either, 1st, A song newly composed: as if he had said, As God gives you fresh occasions to praise him, so do not content yourselves with the old songs or psalms made by former holy men of God, but make new ones suited to these occasions. Or, 2d, Songs renewed, or repeated and continued from day to day.
Related Commentaries of Psalms 33:2
Psalms 33:2-3
2 Praise the LORD with harp: sing unto him with the psaltery and an instrument of ten strings.
3 Sing unto him a new song; play skilfully with a loud noise.