Śatapatha Brāhmaṇa ("of a hundred paths") 9.2.3.17

9.2.3.17

sa upadadhāti | vimāna eṣa divo madhya āsta iti vimāno hyeṣa divo madhya āsta āpaprivānrodasī antarikṣamityudyanvā eṣa imāṃlokānāpūrayati sa viśvācīrabhicaṣṭe ghṛtācīriti srucaścaitadvedīścāhāntarā pūrvamaparaṃ ca ketumityantaremaṃ ca lokamamuṃ cetyetadatho yaccedametarhi cīyate yaccādaḥ pūrvamacīyateti

He sets it up (with, Vâg. S. XVII, 59, 60), 'Measuring he keeps in the middle of the sky,'--for that (sun) indeed keeps measuring in the middle of the sky;--'filling the two worlds and the air,' for even in rising he fills these (three) worlds, 'he scans the all-reaching, the butter-reaching,'--he thereby means the offering-ladles and the offering-grounds;--'between the front and back lights,'--that is, between this world and that one; or that (fire-altar) which is here at this moment being built, and that which was there built at first.