Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 1.2.32

1.2.32

aśvam trayodaśam dadāti /

Paçubandha offerings have seventeen Sāmidhenī verses; therefore he obtains the Iṣṭi and Paçubandha offerings. The offerings of the butter portions have (the word) 'be'; (with the desire) 'Let me be', he establishes the fires; 'May I be' he desires. He, even if being very contemptible as it were he establishes the fires, quickly prospers; he attains enjoyableness, who makes them possessed of (the word) 'be'. The invitatory and offering verses are Virāj verses; prosperity and proper food are the Virāj, (and so they serve) for the winning of the Virāj as prosperity and proper food. These are Gāyatrī verses; Agni is connected with the Gāyatrī and has the Gāyatrī for his metre; verily thus with his own metre he establishes the fires. They are uttered inaudibly; the establishing of the fires is an outpouring of seed; inaudibly is seed outpoured. They are appropriate what in the sacrifice is appropriate, that is perfect; (so they serve) for the perfection of the sacrifice. Twelve (cows) should he give; the year has twelve months; verily (they serve) to make up the year. He gives a horse as thirteenth, to make up the thirteenth month.