Once, when the tzaddik Reb Levi Yitzchak of Berdichev became gravely ill, the Chevra Kadisha visited his home to prepare for his petira. They lit candles and retired to the next room to say Tehillim.
Suddenly they heard a loud noise coming from the room. Frightened, they rushed in and saw their rebbe lying on the floor, seemingly unconscious. They picked him up and placed him back on the bed.
The next day, the rebbe’s illness became worse. Again they began saying Tehillim, only to be interrupted by a loud noise. Again they found the rebbe on the floor and had to put him back into the bed.
On the third day, while waiting outside, they again heard a noise from the room. Entering, they were amazed to see the gaon sitting at the table studying Gemara. He appeared to be completely cured of his illness and looked as if nothing had happened to him.
When they questioned him, he explained as follows: “When I first became very ill, it occurred to me that perhaps G-d was testing me to see if I had strong faith in Him. For G-d, the Creator of all living creatures, surely had the power to heal me. My conscience then warned me that I really did not have supreme faith in Him, and I replied that I did. As proof, I thought, I would attempt to get off the bed and walk to the table and begin to study Torah.
“The first time I tried it, my faith was not strong enough, and I fell down and fainted. The second time, I did not firmly believe I was well, and so I fell down again. But the third time I was so determined to believe that G-d would help that I got off the bed and began to study Torah. And the All-Merciful G-d, seeing my firm belief in Him, helped me, and I immediately became well.”