The Enchiridion

But however strong may be the purposes either of angels or of men, whether of good or bad, whether these purposes fall in with the will of God or run counter to it, the will of the Omnipotent is never defeated; and His will never can be evil; because even when it inflicts evil it is just, and what is just is certainly not evil. The omnipotent God, then, whether in mercy He pities whom He will, or in judgment hardens whom He will, is never unjust in what He does, never does anything except of His own free-will, and never wills anything that He does not perform.