Jaiminīya (Talavakāra) Brāhmaṇa 2-7.274

Its brahman's sāman is the Pārthuraśma, enriched with the sound 'atha'. For a horse runs making, as it were, the sound 'atha-gatha-gatha'. Moreover, a wide bridle (pṛthur raśmiḥ) indeed is fit to hold a horse. And it is fivefold (pāṅkta). For the brahman's sāman of the Mahānāmnī verses is fivefold. It has twenty-one sacrificial posts, twenty-one cubits [in height]. For posts fewer than twenty-one are not fit to lift up these animals. There are six of bilva wood, twelve of khādira wood, and two of pūtudru wood on either side of the fire; that which is pūtudru is the body of Agni. The twenty-first is made of rāyavṛkṣa (rājjudāla) wood. That one stands closest to the fire. Prajāpati among trees is this rājjudāla. The fruits which it has, those are the phalluses; and the slime which it has, that is the semen. Prajāpati indeed is the father; Āditya is the son. The Atirātra consists of all the stomas, for conquering and striding over all the worlds. For all this [world] is just the stomas. Moreover, [thinking]: 'Having attained these individual stomas that we have approached, and having prospered together in them and been established in them, may we reach the completion.'

Now this is the Govinata rite, with the Chandomas as the Pavamāna [stotras]. One desirous of cattle should sacrifice with this. It has both stomas: the odd and the even. Those stomas which are odd, the domestic animals follow them; and those which are even, the wild animals [follow] them. The Chandomas are indeed animals. One who, knowing thus, sacrifices with the Chandoma-pavamāna rite wins both kinds of animals: both domestic and wild. Then this second day has the twenty-one-fold as its pṛṣṭha, so that that praise of the twenty-one-fold should be attained by us.