Taittirīyopaniṣat 01.21
Satyavacā Rāthītaraḥ, one who always speaks truth, said, "satyam", i.e. "truth". Taponityaḥ Pauruśiṣṭiḥ, one who is always engaged in austerity, said, "tapah", i.e. "austerity". Nāka Maudgalyaḥ said, "study and imparting knowledge alone". That indeed is austerity, that indeed is austerity.
Taittirīya Bhāshya 01.21
Truthfulness, self-study, imparting knowledge, and chanting of Vedic hymns - all are austerities. But he who, having thoroughly understood Lord Viṣṇu, explains and repeatedly remembers him, gets liberated. For him, nothing remains to be done.
"When truth and austerity are practiced, all actions are considered accomplished. Especially when it includes self-study and imparting knowledge."
- stated thus as well.
"Whatever sacrifice one studies, that very thing becomes desired for him."
- stated thus by a Vedic statement.
"A brāhmaṇa attains perfection solely through repeated chanting (of mantras), there is no doubt about this. Whether he performs other actions or not, he is still called a compassionate brāhmaṇa."
- stated thus, in the Mahabhārata.
"But he who, having thoroughly understood Lord Viṣṇu, explains and repeatedly remembers, for him nothing remains to be done; he is liberated."
- stated thus in Karmatatva (the principle of action) text.
