As for seeking aid against them through spoken or written formulas whose meaning is unknown, this is not prescribed, especially if they involve polytheism, for that is forbidden. Most of what practitioners of incantations say contains polytheism. They may also recite some of the Quran, openly displaying this while concealing the polytheistic words they utter. Seeking healing through what Allah and His Messenger have prescribed suffices, leaving no need for polytheism or its practitioners.
Although Muslims have disagreed over the permissibility of treatment with forbidden substances, such as carrion and pork, they do not disagree that unbelief and polytheism may never be used as treatments, since they are forbidden in every circumstance. This is not comparable to uttering such words under coercion. That is permissible only when the person’s heart remains firm in faith. For such words to take effect, however, the speaker must mean them in his heart; if he utters them while his heart remains firm in faith, they will have no effect.
If Satan knows that his associate treats the incantations with contempt, he will not assist him. Moreover, someone under coercion is compelled to utter such words, whereas there is no necessity to cure an afflicted person by such means, for two reasons:
First, it may be no more effective than the treatment offered by a practitioner of incantations: it may have no effect and may instead make the sufferer worse.
Second, the truth suffices, leaving no need for falsehood.