The Golden Mountain, by Meyer Levin, , at sacred-texts.com
Reb Baruch, the scribe of Klaminke, tells that once in the midst of winter he rode with the Baal Shem Tov and several of the Rabbi's followers. Evening came. Rabbi Israel said, "Let us stop the wagon and go down and say the evening prayer."
Ice was falling against their faces. Some said, "It is too cold, we will freeze. Let us drive on more quickly, until we come to a house."
But the Master said, "Stop."
So the horses were halted. Rabbi Israel got down from the wagon. And one by one the chassidim got down after him. They were numb with cold. They could hardly stand on their feet.
Rabbi Israel went up to a tree that stood by the road. He touched the tree with his hand, and the tree burst into flame.
The chassidim came close to the tree, they formed a circle around it, and warmed themselves, and prayed the evening prayer.
Then they got into the wagon and rode on.
Reb Baruch says that he turned in the wagon and looked behind him, and saw that the tree continued to burn, and was not consumed.