Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 17.4.7

17.4.7

bahu rātryām upāhvayate / (soma: sodaśin & atiratra)

prepared dish for the gods he tenders the oblation to the gods. He should not undertake it at night; the Ṣoḍaçin is Indra; there is nothing above Indra; much is accomplished at night, the rounds as it were, and the Āçvina (Çastra); therefore he should undertake it on the fourth day; that is the abode of the Ṣoḍaçin; that day concludes with the Ṣoḍaçin as its end. But they say 'Let him undertake it'; the Ṣoḍaçin is the day and night complete; in that they undertake the Ṣoḍaçin it is to make day and night complete.