Jaiminīya (Talavakāra) Brāhmaṇa 2-8.387

They are Ukthyas; cattle are ukthas, [performed] for obtaining cattle.
Regarding this they say: 'The sacrifice is performed in reverse, as it were, when the Viśvajit and Abhijit are Agniṣṭomas,
the Viṣuvant is an Agniṣṭoma, and the Svarasāmans are Ukthyas.
All should be made Agniṣṭomas.
The Agniṣṭoma is the height, the Viṣuvant is the height.
By the height they join the height.
By the height they ascend the height.
The Agniṣṭoma is fiery energy, the Viṣuvant is fiery energy; by fiery energy they join fiery energy; by fiery energy they ascend fiery energy.'
Now the Kāmyakīyas, session-sacrificers having Ayasthūṇa as their householder, sat for a sacrificial session.
Indradyumna Bhāllabeya hastened towards them: 'I will cause my son to chant with the Viṣuvant.'
He arrived when one day of their six-day pṛṣṭhya rite remained unchanted.
He said: 'You have done well what you have chanted.
However, if I had been here, I would have arranged the Viṣuvant otherwise.'
'How, reverend sir, would you have arranged it?' his son said to him.
He said: 'Having undertaken the Abhijit before the six-day pṛṣṭhya rite, I would have proceeded to the Svarasāmans directly from the six-day pṛṣṭhya rite.'

'The six-day pṛṣṭhya rite is the body; the Svarasāmans are the offspring.'

'May offspring come forth from us.'

'Speech indeed are we who are here.'

'May speech come forth from us.'

'When this Abhijit is in between, it stands separating procreation.'

'When they transfer it before the six-day pṛṣṭhya rite, [they think:] "May we procreate from unseparated procreation."'

They indeed are seventeen-fold.