Chāndogya Upaniṣad 8.8.4

8.8.4

tau hānvīkṣya prajāpatir uvāca anupalabhyātmānam ananuvidya vrajato yatara etadupaniṣado bhaviṣyanti devā vā asurā vā te parābhaviṣyantīti \
sa ha śāntahṛdaya eva virocano 'surāñ jagāma \
tebhyo haitām upaniṣadaṃ provāca ātmaiveha mahayya ātmā paricaryaḥ \
ātmānam eveha mahayann ātmānaṃ paricarann ubhau lokāv āpnotīmaṃ cāmuṃ ceti \\808.4\

4. Then Prajāpati glanced after them, and said: ‘They go without having comprehended, without having found the Self (Ātman). Whosoever shall have such a mystic doctrine (upaniṣad), be they gods or be they devils, they shall perish.’ Then with tranquil heart Virocana came to the devils. To them he then declared this mystic doctrine (upaniṣad): ‘One-self (ātman) is to be made happy here on earth. Oneself is to be waited upon. He who makes his own self (ātman) happy here on earth, who waits upon himself—he obtains both worlds, both this world and the yonder.’