Vaisesika Sūtra 2.2.32

लिङ्गाच्चानित्यः शब्दः ॥३२॥

liṅgāccānityaḥ śabdaḥ ॥32॥

[लिङ्गात् (liṅgāt): From the distinguishing mark or characteristic; च (ca): And; अनित्यः (anityaḥ): Impermanent or transient; शब्दः (śabdaḥ): Sound or word;]

The sound produced by the word has a distinguishing mark, but is impermanent.