‘God will maintain the cause of the poor and render justice to the needy. (12)
Psalms 140 to 142 form a small group of three consecutive songs omitted in the Lectionary. All are attributed to David, whose life story should inform our interpretation as we read or sing them. All contain a plea in distress.

The call for rescue in 140, from attack by a violent enemy, repeats the prayers of several other psalms, notably 9 and 10, 11 and 12, and 144. Once again, the bottom line is to seek justice for the poor, those who fall through the safety net. Then surely, continues the writer:
the righteous will give thanks, the upright shall continue in your sight. (13)
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Perhaps the psalmist’s dark vision of human failings has repelled composers. Few useful settings can be found online. When an eighteenth century hymn by Joseph Stephenson turns up, even the title, Preserve me, Lord, from crafty foes: Ps. 140th. for time of War or Persecution is enough to discourage further investigation.
CPDL lists an interesting and ethereal Slavonic Orthodox setting of verses 2 to 4, Да исправитсяby, Da ispravitsya by Tchaikovsky. However the words do not even closely match the psalm text: further inspection reveals that it is 140 in the Vulgate numbering, 141 for us. (qv)
Psalm 140 gains scant attention in PFAS, NCH and TiS. However, Everett provides a good refrain in TEP about justice for the poor. This might be the balm for someone feeling low, or would serve well as a call for social conscience.