Jaiminīya (Talavakāra) Brāhmaṇa 1.143

It emitted the Vairāja.
After that the noise of fire was emitted.
They said: 'We have succeeded through this stotra.'
Therefore, at the stotra of the Vairāja, they churn fire.
One should know this as: 'We have succeeded through this stotra.'
They said: 'Emit further!'
It emitted the Śākvara.
After that the noise of waters was emitted.
They said: 'We have succeeded through this stotra.'
Therefore, at the stotra of the Śākvara, they chant having set down water.
One should know this as: 'We have succeeded through this stotra.'
They said: 'Emit further!'
It emitted the Raivata.
After that the noise of cattle was emitted.
They said: 'We have succeeded through this stotra.'
Therefore, at the stotra of the Raivata, they make the noise of cattle, they cause calves to low to their mothers.
One should know this as: 'We have succeeded through this stotra.'
They said: 'Emit further!'

It did not emit.

It rose upward, like a back, like a hump, thus.

The gods, grasping it, rose upward.

They said: 'Only this much, indeed, this was; this, indeed, is our, the gods', lovely [treasure]!'

Because they said: 'Only this much, indeed, this was; this, indeed, is our, the gods', lovely [treasure],' that is the origin of the Vāmadevya.

That is the nature of the Vāmadevya.

Now this Vāmadevya is the father and the mother of the sāmans.

Indeed, what a son transgresses, the father is its pacifier, the father is its forbidder.

Therefore, that it is performed in the middle is for pacification, for checking.

Now, the sāmans which are chanted: the Vāmadevya is behind them;

and those which are unchanted: it is in front of them;

for the pacification and checking of both of them.