There appear to be a number of spellings and versions of this saying: the above seems to be one of the most popular on Google, and that used in the Wicca article.
Other versions include :
Compare and contrast with Aleister Crowley's 'Do what thou wilt shall be the whole of the Law' - presumably intended as a reaction to the above?
In Wicca, the Rede holds a very similar status to that of the Ten Commandments in Christianity in that it represents the fundamental code by which the morality of one's decisions is judged. Its character is, however, very different, as the Commandments are a list of specific exhortations and prohibitions, while the Rede is a guideline which the individual must interpret to fit each particular situation.