Jaiminīya (Talavakāra) Brāhmaṇa 2-3.33

2-3.33

tadāhuryadidaṃ prāyaṇīyamahastrivṛdācakṣate prāyaṇīyamityadaścaturviṃśaṃ
kathametattrivṛtā prayataṃ bhavatīti
sa brūyādyadevaite catvāriṃśattrivṛtassaṃpadyante tena trivṛtā prayataṃ bhavatīti
atho yaccaturviṃśatyakṣarā gāyatrī teno eveti
tadāhuḥ kathametadvaiṣuvatīyamahaśchandomyaṃ bhavatīti
sa brūyādyāvanti saptānāṃ caturuttarāṇāṃ chandasāmakṣarāṇi tāvatyetasyāhna
stotriyāḥ
tena chandomyaṃ bhavatīti
tadāhuryadupariṣṭādviṣuvataśchandomānupayanti kathaṃ purastādviṣuvataśchandomā upetā
bhavantīti
sa brūyādya evaiṣa ārambhaṇīyasyāhnaścaturviṃśaśchāndomikastomastena
purastādviṣuvataśchandomā upetā bhavantīti
atho yadeva pṛṣṭhyasya dve dve ahanī samaste chandomāssaṃpadyante teno eveti

In this regard they say: 'As to this introductory day, they call the introductory [day] threefold; that one is the twenty-fourth [day]; how does this set forth with the threefold?' He should say: 'Just as these forty become threefold, thereby it sets forth with the threefold; and also because the Gāyatrī has twenty-four syllables, thereby also indeed.' In this regard they say: 'How does this Viṣuvat day become chandomya?' He should say: 'As many syllables as there are in the seven meters increasing by four, so many are the stotriyā verses of this day; thereby it becomes chandomya.' In this regard they say: 'Whereas they undertake the chandomas above the Viṣuvat, how are the chandomas undertaken before the Viṣuvat?' He should say: 'Just as this twenty-fourth chāndomika stoma of the opening day [is used], thereby the chandomas are undertaken before the Viṣuvat; and also because two days of the pṛṣṭhya combined together make up the chandomas, thereby also indeed.'