And the witch who would violate it is more to be pitied than feared. This is a natural law, not merely a social law. Those who understand it will do only beneficial magic in accord with the free will of all sentient beings. I know of and occasionally teach several spells of protection against evil magic. I teach no spells that will harm anyone or anything.
Revenge is inadmissible.
I don't even like having to mention it. The use of magic to do evil is malpractice. Such use rebounds against the evildoer, according to the Law of Three, therefore my love for the student prevents my teaching it. My love for myself prevents me from performing any such thing. The true work of magic is life-affirming, expresses devotion to the Goddess and the God, and is infused with feelings of love, joy, contentment, gratitude, pleasure, and spiritual evolution.