Taittiriya Upanishad 1.9.1

1.9.1

ṛtaṃ ca svādhyāyapravacane ca /
satyaṃ ca svādhyāyapravacane ca /
tapaśca svādhyāyapravacane ca /
damaśca svādhyāyapravacane ca /
śamaśca svādhyāyapravacane ca /
agnayaśca svādhyāyapravacane ca /
agnihotraṃ ca svādhyāyapravacane ca /
atithayaśca svādhyāyapravacane ca /
mānuṣaṃ ca svādhyāyapravacane ca /
prajā ca svādhyāyapravacane ca /
prajanaśca svādhyāyapravacane ca /
prajātiśca svādhyāyapravacane ca /
satyamiti satyavacā rāthītaraḥ /
tapa iti taponityaḥ pauruśiṣṭiḥ /
svādhyāyapravacane eveti nāko maudagalyaḥ /
taddhi tapastaddhi tapaḥ // 1//
iti navamo 'nuvākaḥ //

Righteousness and learning and teaching (are to be practised). Truth and learning and teaching (are to be practised). Austerity and learning and teaching (are to be resorted to). Control of the outer senses and learning and teaching (are to be practised). Control of the inner organs and learning and teaching (are to be resorted to). The fires (are to be lighted up), and learning and teaching (are to be followed). The Agnihotra (is to be performed), and learning and teaching (are to be carried on). Guests (are to be entertained), and learning and teaching (are to be practised). Social good conduct (is to be adhered to), and learning and teaching (are to be followed). Children (are to be begotten), and learning and teaching (are to be carried on). Procreation and learning and teaching (are to be carried on). A grandson (is to be raised), and learning and teaching (are to be practised). Truth (is the thing)—this is what Satyavacā, of the line of Rathītara, thinks. Austerity (is the thing)—this is what Taponitya, son of Puruśiṣṭi, thinks. Learning and teaching alone (are the things)—this is what Nāka, son of Mudgala, thinks. For that indeed is the austerity; for that indeed is the austerity.