Nidāna-shrauta-sūtra 2.11.7

The subsequent [rite] is the sacrifice of one desiring food. / There, he brings in a four-verse [strophe], / saying, 'This is for the praise of food.' / After the āmahīyava comes the ābhīka; / this is for the praise of rain, food produced from rain: the āndhīgava and the arkapuṣpa; / 'This is for the praise of food.' / The subsequent [rite] is the sacrifice of one desiring progeny. / There, he introduces a single verse; / this [verse] containing the word 'bull' (vṛṣaṇvatī) is suitable in the sacrifice of one desiring progeny, declaring the intermediate space, having the intermediate space as their seat: / the gandharvas and apsarases. / The modification of materials that takes place there occurs because of its being a sacrifice of one desiring progeny. / The subsequent [rite] is the sacrifice of one wishing to be cleansed. / Its midday pressing is twelvefold; on both sides are ninefold stomas. / There is a Brāhmaṇa passage to this effect: 'That which is eleventh, that which is twelfth.' / One should enumerate the eleventh [verses] at the morning pressing, the twelfth at the third pressing; / 'Thus the elimination of the poison is accomplished.' / The Adhvaryus also constantly cite this: / 'The stoma is indeed the ninefold, the stoma is the twelvefold; / because from the ninefold they go to the twelvefold, and again from the twelvefold to the ninefold, therefore with this stoma...' / thus he makes it end with the uktha stotras; / 'Thus the elimination of these stotra verses is accomplished.' / For the arrangement of the stoma, he introduces one sāman at midday; / that which is the maidhātitha. / Its origin-verse contains the word 'ariṣṭa', suitable for an expiatory rite. / The modification of materials that takes place here without fear occurs because of its being the sacrifice of one wishing to be cleansed.

The subsequent [rite] is the sacrifice of one desiring cattle.

There, he performs stomas of four rounds.

'Cattle are four-footed.'

There is also a Brāhmaṇa passage constantly [cited]: 'Because he utters the sound hiṅ in four sets of four...'

Then, indeed, he makes opening verses in the anuṣṭubh metre.

'The four-footed [verses] are suitable in the sacrifice of one desiring cattle.'

Being three, he makes them into four gāyatrī verses.

For the vāravantīya chant has the place of the gāyatrī in the fourth stotra verses of the uktha following the yajñāyajñīya.

There is a Brāhmaṇa passage to this effect: 'It is neither an uktha nor an agniṣṭoma.'

And because the vāravantīya is for the praise of cattle,

and also for holding together the stotra verses.

The subsequent [rite] is indeed the sacrifice of one desiring cattle.

There, he brings in a four-verse [strophe].