Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 17.2.26

17.2.26

yajamānac chandasam eva dvipadā / (soma: sodaśin & atiratra)

is the metre of the sacrificer; the Triṣṭubh is might and strength; verily thus he confers might and strength upon the sacrificer. He transposes verses of two Padas containing sixteen syllables and Jagatī verses; verses of two Padas are the metre of the sacrificer; the Jagatī is cattle; verily thus he confers cattle as connected with the Jagatī on the sacrificer. He recites Gāyatrī verses; Gāyatrī verses are breath; verily thus he places breath in himself. He recites a verse of seven Padas; the metres are seven; verily (it serves) to obtain all the metres; moreover, with it the Gāyatrī verses make up four Anuṣṭubh verses; therefore he recites it, for completion.