Śatapatha Brāhmaṇa ("of a hundred paths") 3.2.4.9

3.2.4.9

sa hiraṇyamavadadhāti | eṣā te ṣukra tanūretadvarca iti varco vā etadyaddhiraṇyaṃ tayā sambhavam bhrājaṃ gaceti sa yadāha tayā sambhaveti tayā sampṛcyasvetyevaitadāha bhrājaṃ gaceti somo vai bhrāṭ somaṃ gacetyevaitadāha

He lays down the piece of gold, with the text (Vâg. S. IV, 17), 'This (butter) is thy body, O shining (Agni)! this (gold) is thy light,'--for that gold is indeed light:--'unite therewith and obtain splendour!' When he says, 'Unite therewith,' he means to say, 'Mingle therewith;' and when he says, 'Obtain splendour,'--splendour meaning Soma,--he means to say, 'Obtain Soma.'