Manava Dharmashastra 3.141

Manvarthamuktāvalī 3.141

vedasyaikadeśaṃ mantraṃ brāhmaṇaṃ ca vedarahitāni vyākaraṇādīnyaṅgāni yo vṛttyarthamadhyāpayati sa upādhyāya ucyate|