CHĀNDOGYA UPANISHAD · 5.4.1

असौ वाव लोको गौतमाग्निः ।
तस्यादित्य एव समित् ।
रश्मयो धूमः ।
अहर् अर्चिः ।
चन्द्रमा अङ्गाराः ।
नक्षत्राणि विस्फुलिङ्गाः ॥

asau vāva loko gautamāgniḥ ।
tasyāditya eva samit ।
raśmayo dhūmaḥ ।
ahar arciḥ ।
candramā aṅgārāḥ ।
nakṣatrāṇi visphuliṅgāḥ ॥

'The altar (on which the sacrifice is supposed to be offered) is that world (heaven), O Gautama; its fuel is the sun itself, the smoke his rays, the light the day, the coals the moon, the sparks the stars.

F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)