Mimamsasutra 42.2.24-4

42.2.24-4

vaiśyastome ’kaṇvarathaṃtaraṃ pṛṣṭhaṃ bhavati’ iti śrūyate| tatra- kaṇvarathaṃtarākhyasāmnaḥ prākṛtayoḥ pṛṣṭhastotrasādhanayorbṛhadrathaṃtarayorubhayoḥ sthāne patitatvādubhayasaṃbandhidharmāḥ samuccetavyāḥ| ye tu viruḍhḍharmāḥ- ’uccairgeyam’ ’noccaurgeyam’ ityādayaḥ, te vikalpnyantām| samudradhyānanimīlanādīnāṃ virodhābhāvāt| prakṛtāviva nirdeśamedasyātrābhāvācca samuccayaḥ| iti bhāpyakārasya matam|
vikalpitayoreva dvayoḥ sthāne patitatvādviruḍhḍhadharmasvārasyācca vikalpa eva yuktaḥ, na tu samuccayaḥ| iti vārtikakārasya matam|
tatrobhayatra tattanmataviparītaḥ pūrvaḥ pakṣa unneyaḥ ||

In the Vaiśyastoma it is heard: 'The Kaṇvarathaṃtara is the Pṛṣṭha.' In that case, because the sāman called Kaṇvarathaṃtara has fallen into the place of both the archetypal Bṛhat and Rathaṃtara, which are the means of the Pṛṣṭha-stotra, the ritual details connected with both should be combined. As for the contradictory ritual details, such as 'It should be chanted loudly' and 'It should not be chanted loudly,' let them be optional alternatives; for there is no contradiction in meditating on the ocean, closing the eyes, and so forth. And because there is no difference in specific designation here as there was in the archetypal ritual, they are combined. Such is the opinion of the author of the Commentary.
Because it has fallen into the place of the two which were only ever alternatives to each other, and because of the natural force of the contradictory ritual details, only option is proper, not combination. Such is the opinion of the author of the Vārttika.
In that case, the prima facie view opposite to each of those respective conclusions should be deduced in each case.