Bava Metzia (85a) When R. Zera emigrated to Palestine, he fasted a hundred fasts to forget the Babylonian Gemara, that it should not trouble him. He also fasted a hundred times that R. Eleazar might not die in his lifetime, so that the communal cares should not fall upon him. And yet another hundred, that the fire of Gehenna might be powerless against him. Every thirty days he used to examine himself to see if he were fireproof. He would heat the oven, ascend, and sit therein, but the fire had no power against him. One day, however, the Rabbis cast an envious eye upon him, and his legs were singed, whereafter he was called, ‘Short and leg-singed.’
Bava Basra (75a) R. Johanan explained when he once sat and gave an exposition: The Holy One, blessed be He, will in time to come bring precious stones and pearls which are thirty cubits by thirty and will cut out from them openings ten cubits by twenty, and will set them up in the gates of Jerusalem. A certain student sneered at him: Jewels of the size of a dove's egg are not to be found; are jewels of such a size to be found? After a time, his ship sailed out to sea where he saw ministering angels engaged in cutting precious stones and pearls which were thirty cubits by thirty and on which were engravings of ten cubits by twenty. He said unto them: ‘For whom are these?’ They replied that the Holy One, blessed be He, would in time to come set them up in the gates of Jerusalem. When he came again before R. Johanan he said unto him: ‘Expound, O my master; it is becoming for you to expound; as you said, so have I seen.’ He replied unto him: ‘Raca, had you not seen, would not you have believed? You are then sneering at the words of the Sages!’ He set his eyes on him and the student turned into a heap of bones.