Chandogya Upanishad 7.11.1

7.11.1

tejo vāvādbhyo bhūyaḥ \
tad vā etad vāyum āgṛhyākāśam abhitapati tadāhur niśocati nitapati varṣiṣyati vā iti \
teja eva tatpūrvaṃ darśayitvāthāpaḥ sṛjate \
tad etad ūrdhvābhiś ca tiraścībhiś ca vidyudbhir āhrādāś caranti tasmād āhur vidyotate stanayati varṣiṣyati vā iti \
teja eva tatpūrvaṃ darśayitvāthāpaḥ sṛjate \
teja upāssveti \\711.1\

‘Fire surely is greater than water.’ It is this fire that having seized the air warms up the Ākāśa. Then people say, “It is hot, it is burning hot, it will surely rain.” There, it is fire that shows itself first, and then creates water. It is (because of) this fire that thunders roll, along with lightnings flashing upwards and across; and so people say, “Lightning is flashing, it is thundering, it will surely rain.” There, it is fire that shows itself first and then creates water. Worship fire.