Jaiminīya (Talavakāra) Brāhmaṇa 31.189

Regarding this they say: 'It is contradictory of the Brahma-sāman when it expresses either form.' Because there is 'abhi', they do not depart from the form of the Rathantara. Indra wished to slay Vṛtra. He ran up to Kaṇva: 'O Seer, we run up to you; speak favorably to us here!' Kaṇva saw this sāman. With it he praised. Then Indra slew Vṛtra. He who knows thus slays his hateful rival. Because Kaṇva with this sāman roared the thunderbolt at him with 'abhi', therefore it is called the Kāṇva with the finale 'abhi'. Now these [verses] occur: 'None reached him by deed...'. At this time, the Bṛhatī surpasses the Bṛhatī; the Kakubh surpasses the Kakubh; the Anuṣṭubh surpasses the Anuṣṭubh. That Bṛhatī, being such, turns into a Jagatī. Thereby it surpasses. It oversteps the eighth day, takes hold of the ninth day, and runs back toward the sixth.

Upon them is the Vaikhānasa.

The Vaikhānasas saw these sāmans as the resumption and receding of the sacrifice.

By resumptions, the gods excluded the asuras from the sacrifice.

Now the little seers known as the Vaikhānasas were dear to Indra.

Rahasyu Mārimlava killed them.

Seeking them, [Indra] approached Rahasyu.

He said to him: 'Rahasyu, have you not seen here those little seers known as the Vaikhānasas?'

He said: 'Syo indeed, reverend sir, killed them.'

He said to him: 'Rahasyu, whereas embryo-slaying is hard to confess,

how then did you confess it?'

He said: 'I weighed untruth and embryo-slaying.

Untruth went [down] further.

He went towards truth alone.'

He said to him: 'Choose a boon, you who confessed!'

He said: 'May a Brahmin indeed be born in my progeny.'

Those are these Takṣans of the Rahasyu lineage.

Moreover they say: 'The deities then blamed Indra; they censured Indra: "While you were there, your..."'