Śatapatha Brāhmaṇa ("of a hundred paths") 1.9.1.3

1.9.1.3

devānvā eṣa prīṇāti | yo yajata etena yajñenargbhiriva tvadyajurbhiriva tvadāhutibhiriva tvatsa devānprītvā teṣvapitvī bhavati teṣvapitvī bhūtvāthāśiṣamāśāste tāmasmai devā āśiṣaṃ saṃnamayanti yāmāśiṣamāśāste yo no 'praiṣīditi tasmādvā upariṣṭādyajñasyāśiṣamāśāste

He who sacrifices, assuredly, pleases the gods. Having pleased the gods by that sacrifice,--that is, partly by Rik-verses, partly by Yagus-formulas, and partly by oblations,--he obtains a share among them.
When he has obtained a share among them, then (the Hotri) invokes a blessing (on him); and that (blessing, invoked by him, the gods realise for this sacrificer), knowing as they do that he has pleased them. For this reason also he invokes a blessing after the sacrifice.