Jaiminīya (Talavakāra) Brāhmaṇa 2-8.397

Then Sirinda Pālāli used to say: 'Only on the new-moon day is it to be omitted.
On the new-moon day, indeed, these deities omitted [days];
[thinking:] "Let us omit following the omission of the deities."
These two, indeed, are the sacrificial nights of the year: the full-moon day and the new-moon day.
If they were to omit the full-moon day and the new-moon day, they would deprive the year of its sacrificial essence.
A ninefold Agniṣṭoma only is to be performed.
By that, since its stotras are deficient, it is both omitted and not omitted.'
Then Nagarī Jānaśruteya used to say: 'Only the Ekatrika is to be undertaken.
By that, since its stotras are as if torn, it is both omitted and not omitted.'
Then Āruṇi used to say: 'By these two stomus, the Go and the Āyus, it is both omitted and not omitted.
By that one of the two whose stotras are deficient, it is omitted; by that whose stotras are redundant, it is not omitted.
Therefore these two alone are to be undertaken.'

The Adhvaryu, having taken the soma cup, runs.

He says: 'Turn hither!'

Having uttered the hiṃ sound, having stepped out eastward, standing in front of the Āgnīdhra shed, they chant praise according to the observance of the All-Gods.