Mimamsasutra 42.2.32

42.2.32

(navame- uttarāvarṇavaśena gānādhikaraṇe sūtre 32-33)|
sāmapradeśe vikārastadapekṣaḥ syācchāstrakṛtatvāt ||

(In the ninth [topical section], on chanting according to the syllables of the subsequent verse, the two aphorisms 32–33 [read]:)
In the case of a sāman, the modification should depend on that [syllable], because it is produced by the authoritative text.