Siman 138

(10.) Previously, people did not travel to the Land of Israel by way of Odessa, for they feared to travel that way. And he was the first to travel via Odessa when he traveled to the Land of Israel. And from then onward it became a well-trodden path and everyone travels that way. And similarly with several other things — he began them first and afterwards the world became accustomed to follow after him. Also, when he was in the Land of Israel and was at the graves, there was a grave of a tinok [young child] — and people had always been afraid to enter that cave, saying there was a snake there. There was also something wondrous there — a tree grew on the cave. And he was the first who paid no attention to this and entered there, holding the root of the tree in his hand — for the root was in the ground and passed through the hollow of the cave. And there was no snake there at all. And from then onward everyone goes to that grave. And I myself merited to be there at the aforementioned grave of the tinok and I saw all this with my own eyes. Praise to the living G-d.