Yājñavalkya Śikṣā 24

24

hastādbhraṣṭaḥ svarādbhraṣṭo na vedaphalamaśnute
na karālo na lamboṣṭho nāvyakto nānunāsikaḥ

One who falls from the hand gesture falls from the accent and does not attain the fruit of the Veda. / Neither one who shows frightful teeth, nor one with hanging lips, nor an indistinct speaker, nor a nasalised speaker,