Śatapatha Brāhmaṇa ("of a hundred paths") 3.6.1.26

3.6.1.26

atha havirdhānayoḥ | jaghanārdhaṃ samanvīkṣyottareṇāgnīdhram minoti tasyārdhamantarvedi syādardham bahirvedyatho api bhūyo 'rdhādantarvedi syātkanīyo bahirvedyatho api sarvamevāntarvedi syāttanniṣṭhitamabhimṛśati vaiśvadevamasīti dvayenaitadvaiśvadevaṃ yadasminpūrvedyurviśve devā vasatīvarīṣūpavasanti tena vaiśvadevam

In the north--with regard to the back part of the Soma-carts --he then raises the Âgnîdhra (shed). One half of it should be inside the altar, and one half outside; or more than one half may be inside the altar and less outside; or the whole of it may be inside the altar. When completed, he touches it with, 'Thou art the All-gods’ own!' To the All-gods it belongs, because on the day before (the Soma feast) the All-gods abide in it by the Vasatîvarî water.