Jaiminīya (Talavakāra) Brāhmaṇa 5.18.p1

5.18.p1

atha tvāṣṛtīsāma madhyenidhanaṃ bhavati pratiṣṭhāyai
samudraṃ vā etenārambhaṇaṃ praplavante ya ārbhavaṃ pavamānamupayanti
tadyanmadhyenidhanaṃ bhavati pratiṣṭhityā eva
tasya purastānnidhanasya pratihāramupayanti
prastāvapratihārābhyāṃ vai yajamāno dhṛtaḥ
pradrutamivaitadaharyattrivṛt
tadyatpurastānnidhanasya pratihāramupayantyaprasraṃsāyaiva
indro vṛtraṃ vajreṇādhyasya nāstṛṣīti mayamāno gāḥ prāviśat
tā akāmayantendraṃ janayemeti
tā etāni sāmānyapaśyaṃstvāṣṭrīsāmāni
tairindramajanayan
tāni vā etāni vīrajananāni sāmāni
āsya vīro jāyate ya evaṃ veda
atho paśavo vai tvāṣṭryaḥ
tadyadetāni sāmāni bhavanti paśūnāmevāvarudhyai
tadaiḷe bhavati paśavo vā iḷā paśūnāmevāvaruddhyai
yadu tvāṣṭryo'paśyaṃstasmāttvāṣṭrīsāmetyākhyāyate
abhi priyāṇi pavate canohita
ityabhīti bhavati rathantarasya rūpam
rāthantarametadahaḥ

Then the Tvāṣṭrī-sāman has its finale in the middle for firm support. Truly, they float out into a fathomless ocean who undertake the Ārbhava Pavamāna. That it has its finale in the middle is for firm support. In front of that finale they undertake the pratihāra. By the prastāva and the pratihāra the sacrificer is held fast. Running away as it were is this day, which is the ninefold (trivṛt). That they undertake the pratihāra before the finale is indeed to prevent slipping down. Indra, having hurled the thunderbolt at Vṛtra and thinking "I have not laid [him] low," entered the cows. They desired: "May we give birth to Indra!" They saw these sāmans, the Tvāṣṭrī-sāmans. With them they gave birth to Indra. These indeed are sāmans that generate a hero. A hero is born to him who knows thus. Moreover, the Tvāṣṭrīs are cattle. That these sāmans are used is for the obtaining of cattle. It has an iḷā-finale; cattle are iḷā, for the obtaining of cattle. Since the cows of Tvaṣṭṛ (Tvāṣṭrī) saw it, therefore it is called Tvāṣṭrīsāma. "Toward the dear [seats] he flows, placed in delight"—[the word] "toward" (abhi) is the form of the Rathantara. Belonging to the Rathantara is this day.