The Tosher rebbe and the Satmar Rebbe both used to relate the following story on different occasions:
The Uhjler Rebbe, author of Yismach Moshe, once made a request that Heaven grant him the yiras shomayim of a Tanna. This request was denied on the grounds that he would be unable to withstand such yiras shomayim. He repeated his petition to at least receive the yiras shomayim of an Amora or one of the Geonim; yet again, his request was denied on the very same grounds: He would simply be unable to handle such yiras shomayim.
Finally, he made a third request, to be granted the level of yiras shomayim of the Rambam. This final tefillah was answered. The Yismach Moshe saw however, that he was simply incapable of withstanding such a yiras shomayim. He then davened that it be taken away - and so it was. (Teshuos Tzadikim see also Avodas Avoda Sichos Shemos)
