Albert Barnes Commentary Psalms 71:22

"I will also praise thee with the psaltery, [Even] thy truth, O my God: Unto thee will I sing praises with the harp, O thou Holy One of Israel." — Psalms 71:22 (ASV)

I will also praise you with the psaltery - Margin, as in Hebrew, “with the instrument of psaltery.” The Hebrew word is נבל nebel. In (Isaiah 5:12) it is rendered “viol.” See the notes at that passage. It is rendered “psaltery” in (1 Samuel 10:5); (2 Samuel 6:5); (1 Kings 10:12); and elsewhere. Compare the notes at (Psalms 33:2).

Even your truth - I will make mention of your truth and faithfulness in my songs of praise; or, I will celebrate these in connection with appropriate music.

To you will I sing with the harp - Hebrew, כנור kinnôr. See the notes at (Isaiah 5:12). Compare the notes at (Psalms 33:2).

O you Holy One of Israel - The God of Israel or the Hebrew people; the God regarded by them as most holy, and worshipped by them as their God. This is the first time that this title occurs in the Psalms, but it is common in the prophets, particularly in Isaiah. See (Isaiah 1:4); (Isaiah 5:19), (Isaiah 5:24); (Isaiah 10:20); (Isaiah 12:6). It occurs also in (Psalms 78:41); (Psalms 89:18).