Luke 8

Luke also recounts the story of -

"...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." (New Testament | Luke 8:43 - 46)

The Prophet Joseph Smith related a similar experience. On March 14, 1843, wrote in his journal-

"Elder Jedediah M. Grant enquired of me the cause of my turning pale and losing strength last night while blessing children. I told him that I saw Lucifer would exert his influence to destroy the children that I was blessing, and I strove with all the faith and spirit that I had to seal upon them a blessing that would secure their lives upon the earth; and so much virtue went out of me into the children, that I became weak, from which I have not yet recovered; and I referred to the case of the woman touching the hem of the garment of Jesus. The virtue referred to is the spirit of life; and a man who exercises great faith in administering to the sick, blessing little children, or confirming, is liable to become weakened." (TPJS, pp. 280-81.)

Interesting that virtue can be defined by the "spirit of life".