Set thou a wicked man over him - This commences the imprecatory part of the psalm, extending to Psalms 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. The prayer here seems not to be that the devil or Satan might stand near him as his counselor; but that a man - a real adversary - an accuser - one with a malignant heart - one who would make use of his position to accomplish his own purposes, and to betray the interests of his master, might give him counsel, as seems to have been done in the case of David.