Vaiśeṣika Sūtra 2.2.40

2.2.40

prathamāśabdāt |

prathamāśabhāt—from the word ‘the first; ’

34. From the word, ‘the-first,’ (it follows that Sound is eternal).

The meaning is that the thrice recitation of the first and the last mantra for kindling a sacrificial fire, as enjoined in the text, “The first should be recited three times, the last three times,” is not justified or accountable without the steadiness of Sound.—34.

Candrakānta reads II.ii.34 as Prathamā-ādi-Śabdāt while the meaning remains unchanged. (Ādi = and others, e.g., the second).