LEV898 "You must not desecrate My holy Name" [this verse] – this is among those [prohibitions] (this is a negative commandment one violates when mentioning Hashem's Name in vain, besides neglecting the positive commandment delineated in paragraph 13) that incur excision, as will be explained (paragraph 143 ff). Know that loss and destruction ("loss" may be an allusion to loss of life in this world, and "destruction" to excision in the World to Come) , which is a common phenomenon among the masses, is the result of [improper] speech, for they mention Hashem's Name in vain, and they also utter it without awe. Our Sages, z"l, commented (In his Igeres HaTeshuvah, Rabbeinu Yonah cites Vayikra Rabbah as the source for this), that what is written in the pasuk (Yeshayahu 1:3), "Yisrael did not know [Me]," is referring to just this. Furthermore, they are not meticulous concerning the cleanliness of the place and clean hands (I.e., when mentioning Hashem's Name. By doing so they desecrate His Name, besides violating the prohibition mentioned in paragraph 44). The Sages of Yisrael would ostracize and excommunicate anyone who uttered Hashem's name in vain, and he was also regarded as suspect when taking an oath. They said (Nedarim 7b), "One who hears another uttering Hashem's Name in vain must ostracize him, and if he refuses, then he himself should be ostracized."