Jaiminīya (Talavakāra) Brāhmaṇa 20.103

For that constant burden of theirs is to be carried. Cattle are born with constant calves; therefore pregnant cattle look more radiant, for that constant embryo of theirs is [regarded] by the mother. Now the Vāmadevya: the Vāmadevya is indeed cattle; having praised with it, they indeed become rich in cattle. Now the Bārhadgira and the Rāyovājīya are composed in the paṅkti meter on a paṅkti-day; cattle are indeed fivefold (pāṅkta). Cattle are this day, solely for the acquisition of cattle. And they possess the word 'atha' and have the adhyardhā-iḷā; they are the manifest form of the Śakvarīs on the Śākvara day; thereby they are rich in form. Regarding this they say: 'He today would bathe enjoying, who would find on the other side a firm foundation and a crossing from these.' The Śakvarīs are indeed cows. That which is the word 'atha' and the adhyardhā-iḷā is their firm foundation and crossing on the other side. By means of the definitive Śakvarīs he crosses over evil and attains prosperity, who knows this. Then the sāman of the Acchāvāka is accompanied by iḷā. Cattle are indeed iḷā; in cattle they thus find a firm foundation.

The gods and the Asuras were contending.

Those gods ran up to Prajāpati [saying]: "Give us that meter which is not exhausted,

by which we may overcome the Asuras."

He practiced ascetic toil.

Having practiced ascetic toil, he perceived within himself a thrilling sensation (siṃsimāyat).

Because he perceived a thrilling sensation within himself, that is the simā-nature of the Simās.

He said to them: "Be created!"

[They said:] "By means of what?"

[He said:] "By whatever you desire."

They were created, having risen upward as the very thrill (simānam).

That indeed is their simā-nature.