Jaiminīya (Talavakāra) Brāhmaṇa 1.52

1.52

tadu haike chādimuṣṭimeva nivapanto yanti gārhapatyādāhavanīyādidaṃ
viṣṇurvicakrame ityetayarcā
tadu tathā na kuryāt
yo ha tatra brūyādāsānnvā ayaṃ yajamānasyāvāpsītkṣipre paramāsānāvapsyate
jyeṣṭhyagṛhyaṃ rotsyatīti tathā haiva syāt
itthameva kuryāt
udapātraṃ vaivodakamaṇḍaluṃ vādāya gārhapatyādāhavanīyānninayanniyādidaṃ
viṣṇurvicakrame ityetayaivarcā
devapavitraṃ vā etadyadṛgdevapavitrametadyadāpaḥ
tadyadevātra yajñasyāśāntaṃ bhavati yadamedhyamāpo vai tasya sarvasya śāntiḥ
adbhirevainaṃ tacchamayanti

Regarding this some go scattering handfuls of roof-thatch from the Gārhapatya to the Āhavanīya with this verse: ‘Through this Viṣṇu stepped.’ But he should not do it that way. If someone there were to say: ‘He has scattered [thatch] on the face of the sacrificer; soon someone will scatter [thatch] on his face when he is dead; he will shut out the household headship,’ it would indeed happen so. He should do it in this way only: Taking a water-pot or a water-jug, he should go pouring out water from the Gārhapatya to the Āhavanīya with this very verse: ‘Through this Viṣṇu stepped.’ This which is the verse is a divine purifier, and this which is water is a divine purifier. Whatever unappeased, whatever impure part of the sacrifice is here, water is the pacification of all that. They pacify it with water alone.