The healing powers of the Holy Spirit

… The prayers which were revealed to ask for healing apply both to physical and spiritual healing. Recite them, then, to heal both the soul and the body. If healing is right for the patient, it will certainly be granted; but for some ailing persons, healing would only be the cause of other ills, and therefore wisdom doth not permit an affirmative answer to the prayer.

… The power of the Holy Spirit healeth both physical and spiritual ailments. 

- 'Abdu'l-Baha  (Selections from the Writings of 'Abdu'l-Baha)