From Kings to Chronicles by Way of PsalmsBy Rabbi Jack Abramowitz
This Psalm is “al ha-sheminis,” “on the eighth.” This could be an eight-stringed instrument, as in Psalm 6, or it could be a prophetic reference to the nearly-successful attempt of Queen Ataliah to eradicate David’s descendants, eight generations hence. (Or both!) See II Kings chapter 11 and Rashi on II Chronicles 22:11. In its simplest sense, David is speaking of his own persecution by Saul.
David asks G-d to please save (him? his descendants?), because the righteous are being eradicated. Honest people have disappeared; only two-faced liars remain. David asks G-d to put an end to their falsehoods, both spoken and internal. They think their glib tongues can get them out of any situation. They oppress the poor with impunity. G-d sees this and “arises” to defend the helpless.
G-d’s words are pure as the finest silver. Just as the silver has no impurities, G-d’s words contain no falsehoods; His promise can be relied upon. G-d will protect the innocent victims from their malicious attackers. What a generation it is when such lowly people are respected. The tables will turn and the ones they oppress will be elevated.