Jaiminīya (Talavakāra) Brāhmaṇa 2-3.42

2-3.42

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.'