Albert Barnes Commentary Psalms 143:12

"And in thy lovingkindness cut off mine enemies, And destroy all them that afflict my soul; For I am thy servant." — Psalms 143:12 (ASV)

And of thy mercy ... — Your mercy to me; Your mercy to the world. The destruction of the wicked is a favor to the universe; just as the arrest and punishment of a robber or a pirate is a mercy to society, to mankind; just as every prison is a display of “mercy” as well as of “justice”—mercy to society at large; justice to the offenders.

And destroy all them that afflict my soul — Cut them off; render them powerless to do mischief.

For I am thy servant — Not as a matter of private feeling—not for personal revenge—but because I am in Your service, and it is only by being delivered from these dangers that I can honor You as I would. It is Your own cause, and I ask that they may be cut off “in order” that the service which I might render You may be unembarrassed.