Jaiminīya (Talavakāra) Brāhmaṇa 7.24

7.24

yadu yuktāśvo'paśyattasmādyauktāśvamityākhyāyate
punānassoma dhāraye
tyubhayarūpā bṛhatī bhavati
eṣā ha vā ubhe sāmanī udyayāma
tasmādetāṃ kurvantyeva bṛhatsāmnaḥ kurvanti rathantarasāmnaḥ
tāsu somasāmanī pariṣṭobhavatī bārhate
tasmādbārhate'hani kriyete
vṛṣā vai somo | vṛṣendra | ṣandrametadahaḥ
kṣatraṃ vai somaḥ | kṣatramindra | ṣandrametadahaḥ
reto vai somaḥ prajananametadahaḥ
tadyadete sāmanī etasminnahani kriyete prajanana evaitadretassicyate
anuṣṭhyāsya retassiktaṃ prajāpate ya evaṃ veda
ūrdhveḷamanyadbhavati bṛhato rūpaṃ bārhate'han
bārhatamanyattriṇidhanaṃ mādhyandinasya rūpaṃ pavamānasya dhṛtyai
yadu somo rājā'paśyattasmātsomasāmanī ityākhyāyete
vṛṣā śoṇo abhikanikradadgā
iti vṛṣaṇvatīrbhavanti
bārhataṃ vā etadahastraiṣṭubhaṃ kṣatrasya rūpam

And because Yuktāśva saw [it], therefore it is named Yauktāśva.
"Purifying yourself, o Soma, with a stream..."
—thus the bṛhatī verse is of both forms.
Indeed, this [verse] raised up both sāmans;
therefore, both those belonging to the Bṛhat-sāman make use of it, and those belonging to the Rathantara-sāman make use of it.
Upon them [are sung] the two Soma-sāmans, with refrains (pariṣṭobhavat), in bṛhatī form;
therefore they are performed on the day in bṛhatī form.
Soma is a bull; Indra is a bull; this day belongs to Indra.
Soma is royal power (kṣatra); Indra is royal power; this day belongs to Indra.
Soma is semen; this day is generation.
Now, since these two sāmans are performed on this day, semen is thus poured into the organ of generation.
Properly is the semen of him poured forth, [and] he propagates, who knows thus.
One [sāman] has an elevated iḷā, which is the form of the Bṛhat on the day in bṛhatī form.
The other [sāman] is in bṛhatī form, having three finales, the form of the midday Pavamāna[-stotra], for the stability [of the day].
And because King Soma saw them, therefore they are named the Soma-sāmans.
"The red bull, bellowing loudly to the cows..."
—thus [the verses] contain [the word] "bull".
This day is indeed in bṛhatī form, in triṣṭubh meter, the form of royal power.