Śatapatha Brāhmaṇa ("of a hundred paths") 1.6.2.7

1.6.2.7

yadyu enamupadhāvet | iṣṭyā mā yājayetyetayaiva yājayedyatkāmā vā etamṛṣayo 'juhavuḥ sa ebhyaḥ kāmaḥ samardhyata yatkāmo ha vā etena yajñena yajate so 'smai kāmaḥ samṛdhyate yasyai vai kasyai ca devatāyai havirgṛhyate 'gnau vai tasyai yuhvatyagnā u ceddhoṣyantsyātkimanyasyai devatāyā ādiśettasmādagnaya eva

And if any one (householder) were to resort to him (the Adhvaryu) and say, 'Perform an ishti for me!' let him perform it. Whatever desire the Rishis entertained when they performed that sacrifice, that desire of theirs was accomplished; and accordingly whatever desire he (the sacrificer) entertains in having this sacrifice performed, that desire of his is accomplished. For whatever deity sacrificial food is taken, to that deity they offer it up in the fire (Agni);--and if he is about to offer it up in the fire, why should he announce it to another deity? To Agni alone therefore (it is announced).