Psalms 43:1

Judge me, O God, and plead my cause - ריבי ריבה ribah ribi , a forensic term, properly enough translated, plead my cause, be my counsellor and advocate.

Ungodly nation - The Babylonians; the impious, perfidious, wicked, and deceitful Babylonians.

The deceitful and unjust man - Nebuchadnezzar.