With the word 'Ishvara' he composed the scriptures Shankaracharya's philosophy of language as presented in Brahmasutrabhashya 1.3.28

Writing in the second century BCE, the eminent South Asian grammarian Pata鎣ali conveys a famous story of Indra's victory over Vṛtra due to Vṛtra's mispronunciation of the incantation 'herayo herayaḥ'. 3, 4 Commenting on the merits of grammatical study, Pata鎣ali writes: The demons who were pronouncing 'helayo helaya' [instead of 'herayo herayaḥ' (Oh enemies! Oh enemies!)]5 perished. Therefore, improper [words should not be uttered] by a priest. For a mispronounced [word] is an incorrect word. Grammar should be studied so that we will not [utter] mispronounced word [...] Due either to an incorrect accent or an incorrect phoneme, it is said that an incorrect word does not intimate [the intended] meaning. Just as the word 'indraśatruḥ' [uttered] with the incorrect accent harms the host of the sacrifice, [in the same way] those incorrect words, which are like thunderbolts, [harms the speaker]. [Therefore] grammar should be studied so that we do not pronounce [words with] incorrect accents.6 In the cases of both the demon Vṛtra and the host of the sacrifice, their utterance of incorrect words roused great misfortune, a misfortune directly linked to the unbecoming use of language. The power of language, and specifically the efficacy for scriptural language to bear its fruit according to Pata鎣ali, is cultivated through the instrument of grammar. While the power of language is the subject of a small number of early Vedic passages,7 it was not until the late centuries BCE into the early centuries CE that the subject of language and scriptural interpretation became the central concern of South Asian intellectuals.