The following story comes from the book Inspiring Experiences that Build Faith by Thomas S. Monson, Deseret Book, 1994 pages 133-134

A Hospital Fast

Monson; the hospital fast

While serving as a mission president in Toronto one young missionary became ill.  As the condition became worse the Elder's family flew to Toronto. 

"Late one evening, the father and I entered a hospital room in Toronto, Canada, placed our hands upon the head of the young missionary, and gave him a blessing.  What happened following that blessing was a testimony to me.

"The missionary was in a six-bed ward in the hospital.  The other five beds were occupied by men with a variety of illnesses.  The morning of the missionary’s surgery, his bed was empty.  The nurse came into the room with the breakfast the five men normally ate.  She took a tray over to the patient in bed number and said "Fried eggs this morning and I have an extra portion for you."

"The occupant in bed number one had suffered an accident with his lawn mower.  Other than an injured toe, he was well physically.  He said to the nurse, 'I'll not be eating this morning.'

"All right, we shall give your breakfast to your partner in bed number two.”

As she approached that patient he said “I think I’ll not eat this morning.”

Each of the five men declined breakfast. 

The nurse exclaimed  “Every other morning you eat us out of house and home, and today not one of you wants to eat!  What is the reason?”

Then the man who occupied bed number six answered “You see bed number three is empty.  Our friend is in the operating room under the surgeon’s hands.  He is a missionary for his church, and while we have been patients in this ward he has talked to us about the principles of his church – principles of faith, of fasting wherein we call upon the Lord for blessings.”  He continued.  “We don’t know much about the Mormon church, but we have learned a great deal about our friend, and we are fasting for him today.”

The operation was a success.  When I attempted to pay the doctor he countered.  “Why it would be dishonest for me to accept a fee.  I have never before performed surgery when my hands seem to be guided by a power that was other than my own.  No,” he said “I wouldn’t take a fee for the surgery that Someone on high helped me perform.”

After a few months of recovering at home the missionary returned to Toronto and completed his missionary labors."