Jaiminīya (Talavakāra) Brāhmaṇa 58.369

When the meters sacrificed, the Bṛhatī sang as the Udgātṛ among them.
Then the two following pragāthas were the Prastotṛ and the Pratihartṛ.
The unmeasured meter was the master of the house; the Virāj was the Brahman priest; the Gāyatrī was the Maitrāvaruṇa; the Jagatī was the Hotṛ; the Paṅkti was the Adhvaryu.
Its fifth quarter was the Pratiprasthātṛ; the Triṣṭubh was the Brāhmaṇācchaṃsin; the two meters Uṣṇih and Kakubh were the Neṣṭṛ and the Potṛ; the Anuṣṭubh was the Acchāvāka; the Dvipadā was the Unnetṛ; the Akṣarapaṅkti was the Grāvastut; the Ekapadā was the Subrahmaṇya; the Aticchandas was the Āgnīdhra.
Born of the Gāyatrī is this sacrifice possessing all meters, which is the twelve-day rite.
For the twelve-day rite is extended by all these meters;
all these meters are performed in the twelve-day rite.
Therefore, if one desires an invitation among these meters, then one should desire an invitation among the priests.
When he sacrifices, he sacrifices having become these very meters;
when he officiates at sacrifice, he officiates having become these very meters.
For him who knows this there is no misfortune whatsoever.
Whoever speaks ill of him meets with misfortune.

Regarding this they say: 'In which stoma, in which meter, in which deity is the twelve-day rite ultimately

established?'

He should say: 'In the trivṛt stoma, in the Gāyatrī meter, in the deity Agni

is the twelve-day rite ultimately established.'

For they begin with the trivṛt stoma, with the Gāyatrī meter, with the deity Agni;