The Power of the Holy Spirit
The most potent means of healing is the Power of the Holy Spirit. (72:10)

..This does not depend on contact, nor on sight, nor upon presence.. Whether the disease be light or severe, whether there be a contact of bodies or not, whether a personal connection be established between the sick person and the healer or not, this healing takes place through the power of the Holy Spirit. - Some Answered Questions, p. 295. (72:11)

In a talk with Miss Ethel Rosenberg, in October 1904, 'Abdu'l-Baha said:
The healing that is by the power of the Holy Spirit needs no special concentration or contact. It is through the wish or desire and the prayer of the holy person. The one who is sick may be in the East and the healer in the West, and they may not have been acquainted with each other, but as soon as that holy person turns his heart to God and begins to pray, the sick one is healed. This is a gift belonging to the Holy Manifestations and those who are in the highest station. (73:1)

Of this nature, apparently, were the works of healing performed by Christ and His apostles, and similar works of healing have been attributed to holy men in all ages. Both Baha'u'llah and 'Abdu'l-Baha were gifted with this power, and similar powers are promised to Their faithful followers. (73:3)

End of Quote