He told the despairing mother of the sick man that, once in Halkida, he heard someone talking about some St. John the Russian. The sick man, as he relates, was in such a terrible state that he could not sense, and could not follow what was going on around him. He only heard the word "Russian".
The next day, the man who was healed relates: "My state got even more dangerous. I couldn't sleep, but passed the hours in agony. I was awaiting my death. Then straightaway, I sensed that I wanted to sleep, and I fell into a very deep sleep.
"During the course of my sleep, I saw a strange dream, which I will never forget! I saw that the door of my room opened, and a young man dressed in a white shirt entered. He greeted me, and asked me who I was. I told him that the sickness had taken over me now, and that only death could free me. Then the young man told me in simple words: 'Listen to me. I am St. John the Russian. I will make you well in five days. But you should go venerate at my church. If you can't, then send your wife or your sister or your mother. Have faith and do not fear. In five days you will be well.'
"Immediately, the Saint disappeared from my room. In the morning when I awoke, I felt that my state had improved. This was confirmed by the doctor that visited me that day.
"As soon as I awoke, I called my relatives, and with emotion I related the strange dream. However, I and some of my relatives did not know anything about such a Saint. And only the Priest, Fr. Lambros, informed me that day in reality that I was saved by St. John the Russian, whose body remains whole [and incorrupt] outside of Halkida.
"In five days, I became totally well, and I will never forget the divine intervention of the Saint on behalf of my life. From my great gratitude towards the Saint, and in order to show my faith, I went to venerate the Holy Relics. This miracle occurred in 1937."
(amateur translation of text from source)