Mimamsasutra 42.2.25-3

42.2.25-3

’gosava ubhe kuryāt’ ityādinā gosavādau bṛhadrathaṃtarasāmadvayasādhyaṃ pṛṣṭhastotraṃ vihitam| tatra pṛṣṭhastotrasyaikatvena dharmavyavasthāyā asaṃbhavādbṛhatvuprayadharmāḥ kartavyāḥ| rathaṃtare'pyubhayadharmā ityevaṃ sāṃkaryam| iti cet|
maivam| na hyete pṛṣṭhastotraprayuktā dharmāḥ, kiṃtu sāmaprayuktāḥ| tataḥ- sāmnorbhedāḍhḍharmā vyavatiṣṭhante ||

By such texts as 'In the Gosava he should perform both,' the Pṛṣṭha-stotra to be accomplished by the two sāmans, the Bṛhat and the Rathaṃtara, is enjoined in the Gosava and similar rites. In that context, since the Pṛṣṭha-stotra is one, a distribution of ritual details is impossible; hence the ritual details of both must be performed on the Bṛhat, and the ritual details of both on the Rathaṃtara as well; thus there is intermingling. If it is argued thus—
Not so. For these ritual details are not motivated by the Pṛṣṭha-stotra; rather, they are motivated by the sāmans. Therefore, because the two sāmans are different, their ritual details are distributed.