Psalms 109:6

Set thou a wicked man over him. What worse punishment could a man have? The proud man cannot endure the proud, nor the oppressor brook the rule of another like himself. The righteous in their patience find the rule of the wicked a sore bondage; but those who are full of resentful passions, and haughty aspirations, are slaves indeed when men of their own class have the whip hand of them. For Herod to be ruled by another Herod would be wretchedness enough, and yet what retribution could be more just? What unrighteous man can complain if he finds himself governed by one of like character? What can the wicked expect but that their rulers should be like themselves? Who does not admire the justice of God when he sees fierce Romans ruled by Tiberius and Nero, and Red Republicans governed by Marat and Robespierre? And let Satan stand at his right hand. Should not like come to like? Should not the father of lies stand near his children? Who is a better right hand friend for an adversary of the righteous than the great adversary himself? The curse is an awful one, but it is most natural that it should come to pass: those who serve Satan may expect to have his company, his assistance, his temptations, and at last his doom.

Let Satan stand at his right hand - As the word שטן satan means an adversary simply, though sometimes it is used to express the evil spirit Satan, I think it best to preserve here its grammatical meaning: “Let an adversary stand at his right hand:” i.e., Let him be opposed and thwarted in all his purposes. All the Versions have devil, or some equivocal word. The Arabic has eblees, the chief of the apostate spirits; but the name is probably corrupted from the Greek διαβολος diabolos; from which the Latin diabolus. the Italian diavolo, the Spanish diablo, the French diable, the Irish or Celtic diabal, the Dutch duivel, the German teufel, the Anglo-Saxon deofal, and the English devil, are all derived. The original, διαβολος, comes from δια βαλλειν to shoot or pierce through.

Set thou a wicked man over him - This commences the imprecatory part of the psalm, extending to Psa 109:20. The first thing that the psalmist asks is, that his foe might be subjected to the evil of having a man placed over him like himself: a man regardless of justice, truth, and right; a man who would respect character and propriety no more than he had himself done. It is, in fact, a prayer that he might be punished “in the line of his offences.” It cannot be wrong that a man should be treated as he treats others; and it cannot be in itself wrong to desire that a man should be treated according to his character and deserts, for this is the object of all law, and this is what all magistrates and legislators are endeavoring to secure. And let Satan stand at his right hand - As his counselor and adviser. The language would be properly applicable to one who had been a counselor or adviser to a king in the administration of the government; and the prayer is, that he might know what it was to have such a one as his counselor and adviser. The language used would seem to make it not improbable that David here refers particularly to someone who had occupied this position in reference to himself, and who had betrayed his trust; who had given him crafty and malignant counsel; who had led him into bad measures; who had used his position to promote his own interests at the expense of his master’s. David had such counselors, as anyone in authority may have. The prayer, then, would be, that such a man might be punished in his own line; that he might know what it was to have a bad and wicked adviser. The word rendered “Satan” - שׂטן śâṭân - is in the margin rendered “adversary.” In the Septuagint it is διάβολος diabolos; in the Vulgate, “diabolus.” See the notes at Job 1:6, for its meaning. […]