(Devarim 32:3) "When I call out the name (shem) of the L-rd, ascribe greatness to our G-d.": We find, then, that Moses (in awe of the L-rd) did not mention the name of the L-rd (yod-keh-vav-keh) until after twenty-one words (from "Ha'azinu" until shem"). From whom did he learn to do this? From the ministering angels, who do not mention the name of the L-rd until after three "holies," viz. (Isaiah 6:3) "And one would call to the other and say 'Holy, holy, holy is the L-rd of hosts.'"
Moses reasoned: It suffices that I place fewer than seven (words before the name of the L-rd) to be like [i.e., to emulate the awe of]) the ministering angels. Now does this not follow a fortiori, viz.: If Moses, the wisest of the sages, the greatest of the great, did not mention the name of the L-rd until after twenty-one words, then one who mentions the name of the L-rd in vain, how great (is his sin)!
R. Shimon b. Yochai says: Whence is it derived that one should not say "to the L-rd a burnt-offering," "to the L-rd a meal-offering," "to the L-rd peace-offerings," but "a burnt-offering to the L-rd," "a meal-offering to the L-rd," "peace-offerings to the L-rd"? From (Vayikra 1:2) "an offering to the L-rd" (rather than "to the L-rd an offering.") Now does this not follow a fortiori, viz.: If (in respect to) these (offerings) which are consecrated to Heaven, the L-rd says: Let My name not be ascribed to them until they have been consecrated, then one who mentions the name of the L-rd in vain, and in an inappropriate place, how great (is his sin)!