Mimamsasutra 90.2

90.2

ācāntena kartavyam; yajñopavītinā kartavyam; dakṣiṇācāreṇa kartavyam ityevaṃlakṣaṇāny udāharaṇāni. kim etāni śrutiviruddhāni na kartavyāni utāviruddhāni kāryāṇīti. [69] iti cet paśyasi, tair apy anuṣṭhīyamānair vaidīkaṃ kiṃcin na kupyati, tasmād aviruddhānīti.

Examples of this characteristic are: 'One should perform [the rite] having sipped water'; 'One should perform [it] wearing the sacred thread'; 'One should perform [it] using the right side/hand.' Are these, being contradicted by direct scriptural statement, not to be performed, or, being not in conflict, to be carried out? If you think that even when they are performed nothing prescribed by the Veda is disturbed, therefore they are not in conflict—