Aitareyabrahmana 5.16

5.16

Whatever contains 'i' (approach) and 'pra' (forward) is a characteristic of the seventh day. For what the first day is, that again is this seventh day. What contains 'yunkta' (yoked), what contains 'ratha' (chariot), what contains 'āśu' (swift), what contains 'piba' (drink), where the deity is explicitly mentioned in the first quarter-verse, where this world is alluded to, what contains 'jāta' (born), what is unexpressed, what refers to the future, what is a characteristic of the first day—these indeed are the characteristics of the seventh day.

'From the ocean the honey-sweet wave arose': this is the ājya [śastra] of the seventh day, unexpressed, on the seventh day, a characteristic of the seventh day.
Speech indeed is the ocean.
Speech is not exhausted, nor is the ocean exhausted.
In that this is the ājya [śastra] of the seventh day, they thereby extend the sacrifice from the sacrifice itself; they thereby return to speech for continuity.
Those who proceed knowing thus proceed by continuous, uninterrupted three-day periods.
Indeed, the stomās are exhausted, the metres are exhausted on the sixth day.
Just as in that world they baste the cut-off portions again with melted butter for freshness, even so they return to the stomās and to the metres again for freshness.
In that this is the ājya [śastra] of the seventh day, it is in the triṣṭubh metre. This three-day period has the triṣṭubh for its morning pressing.

'Come, O Vāyu, drinker of the pure, adorn our sacrifice', 'With which you go forward to the donor', 'Come to our sacrifice with your teams numbering a hundred', 'The swift presser has stepped forward in the rites', 'Which wind-borne, Indra-intoxicating [draughts]', 'Which hundred teams you have, which thousand', 'When Mitra and Varuṇa contended', 'Come, O Nāsatyas, with your chariot rich in cattle', 'Come to us, O god, with might, O powerful one', 'Forward do the godly worship you at the sacrifices', 'Forward did it flow with its surging food': this is the praüga [śastra]. What contains 'i' and 'pra' on the seventh day is a characteristic of the seventh day. And it is in the triṣṭubh metre; this three-day period has the triṣṭubh for its morning pressing.

'To you like a chariot for help', 'This pressed juice, O Vasu', 'O Indra, come right near', 'Let Brahmaṇaspati go forth', 'Agni is the leader', 'You, O Soma, through your wisdom', 'The waters swell', 'Forward to great Indra for you': this is the same extension as the first day, on the seventh day, a characteristic of the seventh day.

'With what splendour, being of equal age and belonging to the same nest': this hymn, containing 'born' in 'neither one being born attains [him], nor one born', is a characteristic of the seventh day on the seventh day. And that is the Kayāśubhīya hymn.
This indeed is the hymn of agreement, of continuation, namely the Kayāśubhīya.
By this indeed did Indra, Agastya, and the Maruts come to an agreement.
That he recites the Kayāśubhīya is just for agreement.
And it confers long life.
Therefore, for whomever he holds dear, he should recite the Kayāśubhīya for him.
And it is in the triṣṭubh metre.
With its verse having a firm foundation, he sustains the pressing; he does not depart from his proper seat by this.

'Magnify that ram who finds the light': this hymn, containing 'chariot' in 'like a swift horse, a chariot speeding to the call', is a characteristic of the seventh day on the seventh day. And that is in the jagatī metre.
The jagatī verses indeed carry the midday [pressing] of this three-day period.
That metre indeed carries [it] into which the nivid is inserted.
Therefore he inserts the nivid into jagatī verses.
Copulative pairs of hymns are recited: both triṣṭubh and jagatī verses.
Cattle indeed are a copulative pair; the chandomas are cattle, for the attainment of cattle.

'You indeed we call upon', 'For you come, O active one': these form the bṛhat-pṛṣṭha on the seventh day, which is the same as that of the sixth day.
What is the rathaṃtara is the vairūpa; what is the bṛhat is the vairāja; what is the rathaṃtara is the śākvara; what is the bṛhat is the raivata.
That it is the bṛhat-pṛṣṭha is because they support the bṛhat with the bṛhat itself, to prevent a rupture of the stomā.
If it were the rathaṃtara, there would be a rupture.
Therefore the bṛhat alone is to be performed.

'What has been won' is the fixed insertion-verse.
He turns back in accordance with the womb of the rathaṃtara with 'Unto you, O hero, we shout praise'.
For this day is connected to the rathaṃtara by its proper seat.
'Drink of the pressed, sapful [draught]' is the sāmapragātha, containing 'piba' (drink) on the seventh day, a characteristic of the seventh day.
'That swift courser sped by the gods' is the fixed Tārkṣya hymn.