Sing to the Lord with the harp - A song or psalm accompanied by the harp. On the harp. See the notes at Isaiah 5:12.

And the voice …

Sing ... —Rather, Play to Jehovah on a harp, on a harp, and with melodious sound of music.

Sing unto the Lord with the harp
Playing upon that at the same time: here and in the following verse is an allusion …

Let all people rejoice in the establishment of Christ's kingdom, for all may benefit from it. The different orders of rational creatures in the uni…