These three psalms tell of moments of grief, fear, shame or anger caused by conflict of one sort or another. While they all on first reading have a flavour of violence, and all are omitted from the weekly lectionary readings, they should not be ignored. They actually argue for reliance on divine truth and protection rather than the sword.
The psalmist first draws strength from divine guidance and support in the story of Exodus. The conquering of the promised lands is not attributed to armed force. In a precursor to Jesus’ command to Peter in the Garden of Gethsemane to put down his sword, so here:
I do not rely on my bow, and my sword does not give me the victory; surely you gave us victory (vs. 6, 7)
The psalmist is aware that God searches our hearts (v. 21; both this verse and the next are quoted by Paul in Romans 8). The remainder of the song is a lament at some grievous reverses. Despite humiliation:
yet we have not forgotten you nor strayed from your covenant. Our heart never turned back (vs. 17, 18)
Settings are few in the ether but Thomas Tomkins (1572-1656) used verses 5 to 9 for an attractive composition for solo bass and choir. Verses 6 and 7 quoted above are also used as the refrain in The Emergent Psalter.
Little will be said about this song, as it is virtually a repeat of Psalm 14 (qv. this post>). Paul quotes these psalms in Romans 3 to emphasise grace and love, rather than justification under the law.
In this psalm, the first of seven ‘skips’ in a row, the grief is caused by false witness or betrayal by someone who was considered a friend:
My companion hurt a friend and broke a covenant with speech softer than butter — but war is in his heart. (v. 20, 21)
If nothing else, this psalm should encourage us to ‘speak the truth in love’ (Eph.4:15) — and then stick to it. We are also advised, as in I Peter 5:7, to cast our burdens upon God.
Several of the settings in Choralwiki use just a few verses, often 2 to 4 which are a plea to be heard in times of anguish. The show-stopper is one by Giovanni Gabrieli (1554 ‒ 1612) for 12 parts in three choirs. However, there are also four-part settings by Lassus and Mendelssohn.