Jaiminīya (Talavakāra) Brāhmaṇa 2-3.42

2-3.42

tasmāttryaheṇānyattanumahe tryaheṇānyat
sa dvyahassanṣaḍaho bhavati
tadūrdhve goāyuṣī bhavata ūrdhvo daśarātraḥ
taddhaitadeke vihṛte goāyuṣī upayantyupariṣṭādviśvajita āyuḥ purastāddaśarātrasya
gām
evamajāmīti
atho evamevaitayoḥ puropāyayanam
tatpramattā naimiśīyā atīyuḥ
te'tra purastāddaśarātrasya sahopeyuḥ
tata idamarvācīnamevopayanti
tadu hovāca śāṭyāyaniḥ prāṇāpānāvetau yadgoāyuṣī
annapāne te vicchindanti ye viharanti
atho eṣa vāva devayānaḥ panthā yadgoāyuṣī
svarga eṣa loko yaddaśarātraḥ
ta etena devayānena pathaitaṃ svargaṃ lokaṃ gacchanti
atha ya ete viharantyetaṃ devayānaṃ panthānaṃ vicchindanti te na kiṃ cana
vyaśnuvate
tasmātsahaivopetye iti

Therefore we perform one [period] with a three-day rite, and another with a three-day rite. Being a two-day rite, it becomes a six-day rite. Thus the Go and Āyus become ascending; the ten-day rite becomes ascending. On this point, some undertake the Go and Āyus separated: the Āyus after the Viśvajit, the Go before the ten-day rite, [saying,] 'So that it is not monotonous; moreover, such was their earlier practice.' Careless in this regard, the Naimiśīyas transgressed. Here, before the ten-day rite, they undertook [them] together; thence they perform this descending rite alone. Regarding this, Śāṭyāyani said: 'These two, the Go and the Āyus, are out-breath and in-breath. Those who separate them cut off food and drink. Furthermore, these two, the Go and the Āyus, are indeed the path of the gods; this ten-day rite is the heavenly world. By this path of the gods they go to this heavenly world. But those who separate them cut off this path of the gods; they do not attain anything. Therefore they must be undertaken together.'