JC - Chapter 20

As Elder Talmage related many of the miraculous healings performed by the Savior, he writes of where -

"a woman having an issue of blood twelve years, which had spent all her living upon physicians, neither could be healed of any,
44 Came behind him, and touched the border of his garment: and immediately her issue of blood stanched.
45 And Jesus said, Who touched me? When all denied, Peter and they that were with him said, Master, the multitude throng thee and press thee, and sayest thou, Who touched me?
46 And Jesus said, Somebody hath touched me: for I perceive that virtue is gone out of me.
47 And when the woman saw that she was not hid, she came trembling, and falling down before him, she declared unto him before all the people for what cause she had touched him and how she was healed immediately.
48 And he said unto her, Daughter, be of good comfort: thy faith hath made thee whole; go in peace."  (New Testament | Luke 8:43 - 48)

Modern revelations states -

"...to some it is given to have faith to be healed;
20 And to others it is given to have faith to heal."  (Doctrine and Covenants | Section 46:19 - 20)

As so stated, such faith is a gift of the Spirit.  But I also noted that even though the woman was healed, it seems apparent that nonetheless, the Savior wanted her to confess what she had done so she could be clear of all conscience.

Of this event, Elder Talmage commented -

"Observe the significant assertion, “Thy faith hath made thee whole.” Faith is of itself a principle of power; and by its presence or absence, by its fulness or paucity, even the Lord was and is influenced, and in great measure controlled, in the bestowal or withholding of blessings; for He ministers according to law, and not with caprice or uncertainty. We read that at a certain time and place Jesus “could there do no mighty work” because of the people’s unbelief.bb Modern revelation specifies that faith to be healed is one of the gifts of the Spirit, analogous to the manifestations of faith in the work of healing others through the exercise of the power of the Holy Priesthood...

That there was an actual giving of His own strength to the afflicted whom He healed is evident from the present instance. Passive belief on the part of a would-be recipient of blessing is insufficient; only when it is vitalized into active faith is it a power; so also of one who ministers in the authority given of God, mental and spiritual energy must be operative if the service is to be effective."