Śatapatha Brāhmaṇa ("of a hundred paths") 2.1.1.6

2.1.1.6

athoṣāntsambharati | asau ha vai dyaurasyai pṛṭhivyā etānpaśūnpradadau tasmātpaśavyamūṣaramityāhuḥ paśavo hyevaite sākṣādeva tatpaśubhirevainametatsamardhayati te 'muta āgatā asyām pṛthivyām pratiṣṭhitāstamanayordyāvāpṛthivyo rasam manyante tadanayorevainametaddyāvāpṛthivyo rasena samardhayati tasmādūṣāntsambharati

He then brings salt. Yonder sky assuredly bestowed that (salt as) cattle on this earth: hence they say that salt soil is suitable for cattle. That (salt), therefore, means cattle; and thus he thereby visibly supplies it (the fire) with cattle; and the latter having come from yonder (sky) is securely established on this earth. Moreover, that (salt) is believed to be the savour (rasa) of those two, the sky and the earth: so that he thereby supplies it (the fire) with the savour of those two, the sky and the earth. That is why he brings salt.