Break thou the arm - Destroy his power, deprive him of his influence, that he may be no longer able to oppress.
Seek out his wickedness till thou find none - All his public haunts and private ways shall be investigated; thou wilt bring all his villanies to light, and continue to inflict punishment, while there is a crime to punish. Or, "Continue to judge and punish transgressors, till not one is to be found." This agrees with the following verse.
Break thou the arm of the wicked - The arm is the instrument by which we effect a purpose, and especially in wielding a sword or a spear, as in battle; and if the arm is broken, we are powerless. The psalmist, therefore, prays that God would render the wicked, in this respect, powerless.
And the evil man - Of all the evil, or the wicked. In regard to the prayer here, see the note at Psalm 5:10.
Seek out his wickedness until thou find none - Until it is all punished; until there has been a full recompense. This is a wish that no wicked act of his should be forgotten; that exact justice should be rendered. If it is right to punish the wicked at all, it is right to deal with them just as they deserve; if any wickedness may properly be punished, all may be; and, whatever may occur, the sinner may be assured that he will not be punished merely for a part of his sins. If God punishes the wicked at all, there will be nothing left unpunished.