Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.2.46

2.5.2.46

trīṇi samiṣṭṛyajūṃṣi juhoti | tūṣṇīmeva pratiprasthātā srucam pragṛhṇāti tadye vaiśvadevena yajamānayorvāsasī parihite syātāṃ te evātrāpi syātāmathāsyai vāruṇyai payasyāyai kṣāmakarṣamiśramādāyāvabhṛthaṃ yanti varuṇyaṃ vā etannirvaruṇatāyai tatra na sāma gīyate na hyatra sāmnā kiṃ cana kriyate tūṣnīmevetyābhyavetyopamārayati

He (the Adhvaryu) performs the three Samishtayagus (with the respective texts); the Pratiprasthâtri takes up his spoon (and performs those oblations) silently.--The same garments, worn by the sacrificer and his wife at the Vaisvadeva, should be put on also on this occasion. They now take (the havis) mixed with the burnt scrapings of the Varuna curds, and betake themselves to (the place of) the expiatory bath (avabhritha). This (ablution) stands in relation to Varuna, (being performed) with a view to deliverance from Varuna's power. No Sâman-hymn is sung on this occasion, for at this (sacrifice) nothing whatever is performed with a Sâman-hymn. Having silently walked thither and entered (the water), he (the Adhvaryu) immerses (the vessel containing the scrapings).