For they speak against thee wickedly
Against his being, his perfections, his purposes, his providences, his doctrines, ordinances, ministers, and people; or "they speak of thee for wickedness" F2, they made mention of the name of God to cover their wickedness, pretending to fear God and love him, to have a reverence of him and serve him, putting on a form of godliness, but denying the power thereof;
[and] thine enemies take [thy name] in vain:
either by profane swearing, or by false swearing. The Targum interprets both clauses of swearing deceitfully and vainly; or "he", that is, everyone that is "lifted up to vanity [are] thine enemies" F3, whose hearts are lifted up to vanity, idols, riches, self-righteousness, sensual lusts and pleasures; these are the enemies of God, are estranged from him, hold friendship with the world, harbour his enemies, love what he hates, hate what he loves, and commit acts of hostility against him. The Septuagint, Vulgate Latin, Syriac, Arabic, and Ethiopic versions, read, "they take thy cities in vain".
F2 Or "to a mischievous purpose"; so Ainsworth.
F3 (Kyde awvl awvn) "qui elatus est ad vanitatem, hostes tui sunt", De Dieu.