Śatapatha Brāhmaṇa ("of a hundred paths") 1.7.3.9

1.7.3.9

te hocuḥ | yattvayyamutra satyayakṣmahi tannaḥ sviṣṭaṃ kurviti tadebhyaḥ sviṣṭamakarottasmātsviṣṭakṛta iti

They (the gods) said, 'What we have offered unto thee who art in yonder place, do thou render that well-offered (svishta) for us!' He made it well-offered for them; and this is the reason why (it is offered) to (Agni as) the Svishtakrit.