Śatapatha Brāhmaṇa ("of a hundred paths") 7.4.1.45

7.4.1.45

tadāhuḥ | naitasya puruṣasya bāhū kuryādetau vā asya bāhū ye ete srucau nedatirecayānīti sa vai kuryādevaitau vā asya bāhū anvete srucāvatho etau pakṣāvatho yānyetasminnagnau rūpāṇyupadhāsyanbhavati yāntstomānyāni pṛṣṭhāni yāni candāṃsyetayoreva sā saṃskṛtiretayorvṛddhistasmādu kuryādevaitasya puruṣasya bāhū

As to this they say, 'Let him make no arms to this (gold) man, lest he should cause him to be redundant; for these two spoons are (in lieu of) his arms.' Let him nevertheless make (him with arms), for those two spoons are (merely) after the manner of the two arms. Moreover, those two (arms of Agni) are wings; and whatever forms, whatever stomas, whatever prishthas, whatever metres he will be applying to that fire-altar, that will be the perfection, that will be the growth of those two: let him therefore make arms to that (gold) man.