Brahmavaivartapurana 3.122.14

Brahmavaivartapurāṇa 3.122.14

guruścajñānodgiraṇājjñānaṃ syānmantratantrayoḥ .
sa ca mantraśca tattantraṃ bhaktiḥ syāddhruvayoryataḥ .. 14 ..