Shatapatha Brahmana 8.7.1.20

8.7.1.20

tānyetāni jyotīṃṣi | tadyadetā evamupadadhātyetānyevaitajjyotīṃṣi samyañci dadhāti tasmādita ūrdhvo 'gnirdīpyate 'rvāṅsāvādityastapatyantarikṣe 'yaṃ tiryaṅ vāyuḥ pavate

These (three) then are the lights;--and when he lays down these (three Visvagyotis bricks) in this way, he thereby sets up those same lights so as to face each other; and hence the fire blazes upwards from this (earth), and yonder sun shines downwards, and that wind blows sideways in the air.