Śatapatha Brāhmaṇa ("of a hundred paths") 2.1.1.5

2.1.1.5

atha hiraṇyaṃ sambharati | agnirha vā apo 'bhidadhyau mithunyābhiḥ syāmiti tāḥ sambabhūva tāsu retaḥ prāsiñcattaddhiraṇyamabhavattasmādetadagnisaṃkāśamagnerhi retastasmādapsu vindantyapsu hi prāsiñcattasmādenena na dhāvayati na kiṃ cana karotyatha yaśo devaretasaṃ hi tadyaśasaivainametatsamardhayati saretasameva kṛtsnamagnimādhatte tasmāddhiraṇyaṃ sambharati

He then brings (a piece of) gold. Now Agni at one time cast his eyes on the waters: 'May I pair with them,' he thought. He came together with them; and his seed became gold. For this reason the latter shines like fire, it being Agni's seed. Hence it (gold) is found in water, for he (Agni) poured it into the water. Hence also one does not cleanse oneself with it, nor does one do anything else with it. Now there is splendour (for the fire): for he thereby makes it to be possessed of divine seed, bestows splendour on it; and sets up a fire completely endowed with seed. That is why he brings gold.