BṚHADĀRAṆYAKA UPANISHAD · 2.1.18

स यत्रैतत् स्वप्न्यया चरति ते हास्य लोकाः ।
तद् उतेव महाराजो भवत्य् उतेव महाब्राह्मणः ।
उतेवोच्चावचं निगच्छति ।
स यथा महाराजो जानपदान् गृहीत्वा स्वे जनपदे यथाकामं परिवर्तेतैवम् एवैष एतत् प्राणान् गृहीत्वा स्वे शरीरे यथाकामं परिवर्तते ॥

sa yatraitat svapnyayā carati te hāsya lokāḥ ।
tad uteva mahārājo bhavaty uteva mahābrāhmaṇaḥ ।
utevoccāvacaṃ nigacchati ।
sa yathā mahārājo jānapadān gṛhītvā sve janapade yathākāmaṃ parivartetaivam evaiṣa etat prāṇān gṛhītvā sve śarīre yathākāmaṃ parivartate ॥

But when he moves about in sleep (and dream), then these are his worlds. He is, as it were, a great king; he is, as it were, a great Brâhmana; he rises, as it were, and he falls. And as a great king might keep in his own subjects, and move about, according to his pleasure, within his own domain, thus does that person (who is endowed with intelligence) keep in the various senses (prânas) and move about, according to his pleasure, within his own body (while dreaming).

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)