Kaṭha Upaniṣad · 1.3.7

नाचिकेतमुपाख्यानं मृत्युप्रोक्तं सनातनम् । उक्त्वा श्रुत्वा च मेधावी ब्रह्मलोकमहैति सः ॥ ७॥

nāciketam upākhyānaṃ mṛtyuproktaṃ sanātanam | uktvā śrutvā ca medhāvī brahmalokam ahai saḥ

The tale of Naciketas, taught by Death and ancient as time — having recited and heard it, the sage reaches the world of Brahman.

This verse presents the Nāciketopākhyāna (tale of Naciketas) as a sanātana-dharma (eternal teaching), transmitted by Yama (Death personified) himself. Whoever recites (uktvā) and whoever hears (śrutvā) this teaching with intelligence (medhāvī) reaches Brahmaloka — not just an elevated plane of existence, but union with Brahman. In the context of yoga, this underscores that the study and transmission of these teachings are an integral part of sādhanā (spiritual practice).