Nidanasutra 2.4.6

'For these are not caused by transposition;
these belong to the application of the nine-day rite,' says Dhānañjayya.
How, when not intending to complete the nine-day rite, could one perform the applications of the nine-day rite?
In that case, these two [verses] are permanently present according to the rule of the abhiplava; with the permanent [verses] he consolidates the pṛṣṭha sāman of the second [day], the final midday chant according to the rule of the abhiplava: 'This six-day period is permanent.'
There, those very chants that are in the abhiplava are the consolidated ones;
this other chant is just the janitra.
Those who desire their own origins have that performed.
[The question is asked:] 'How is the abhīvarta chant performed in the pṛṣṭhya rite?'
'It is not to be performed,' says Śaucivṛkṣi;
'in five months, the pragāthas in the bṛhatī metre are obtained;
this attainment is accomplished from somewhere other than the pṛṣṭhya rite.'
'It is to be performed,' says Gautama;
for there is a saying: 'Whatever sāman they omit, from that world of heaven they would fall.'
Or he declared this existing [sāman] in the pṛṣṭhya rite;
for none remove it from the abhiplava.
There, on the bṛhatī verses, we arrange the kāleya as a second chant;
in it, it has the form of a continuity.
[The question is asked:] 'How in the abhijit sacrifice?'
'It is not to be performed,' says Śaucivṛkṣi;
'it is indeed to be performed,' says Gautama;
that is explained by the pṛṣṭhya rite itself.
Furthermore, this one-day rite, thus arranged, arrives having the abhīvarta chant at midday, having the abhīvarta chant at midday.

Thus ends the fourth section.