Shatapatha Brahmana 4.5.9.1

4.5.9.1

tadyatraitaddvādaśāhena vyūḍhacandasā yajate | tadgrahānvyūhati vyūhata udgātā ca hotā ca candāṃsi sa eṣa prajñāta eva pūrvastryaho bhavati samūḍacandāstadaindravāyavāgrāngṛhṇāti

When he performs a twelve days’ sacrifice with transposed metres (Dvâdasâha vyûdhakhandas), then he (the Adhvaryu) transposes the grahas (cups of Soma); and both the Udgâtri and the Hotri transpose the metres. Now there is first that normal Tryaha (triduum), with settled metres: there he draws the cup beginning with the Aindravâyava.