Jaiminīya (Talavakāra) Brāhmaṇa 1.179

The gods and the Asuras contended over the sacrifice.
The gods drove the Asuras out from the sacrifice.
Those Asuras, tearing out the sap and vital power of the three soma pressings, entered into blind darkness.
Whatever is beyond the Agniṣṭoma, that indeed is blind darkness.
Whatever is beyond the year, that is blind darkness.
The sacrifice is just as extensive as the Agniṣṭoma.
The year is just as extensive.
Twelve indeed are the stotras of the Agniṣṭoma; twelve are the months of the year.
Twelve are the stotras, twelve the recitations.
Twelve are the waxing fortnights, twelve the waning fortnights.
Now, whatever is beyond that, that is blind darkness.
Into that they entered.
The gods went down after the Asuras.
They stood up against those Asuras with these very ukthas.
In that they stood up against them with ukthas, that is the uktha-nature of the ukthas.
They drove them out from there.
They entered into blind darkness, into night itself.
Indra said: 'Who and I shall go down after this?'

'I too,' said Varuṇa.

'I will hold light for the two of you,' said Agni.

The two went down after [them].

The two brought out one third.

With it they replenished the morning pressing.

Therefore they praise on verses addressed to Agni.

[A hymn] addressed to Indra and Varuṇa is recited after.

Therefore also they praise on Gāyatrī verses.

For the morning pressing belongs to the Gāyatrī.

He alone said: 'Who and I shall go down after this?'

'I too,' said Bṛhaspati.

The two went down after [them].

The two brought out one third.

With it they replenished the midday pressing.