Yāska's Nirukta 7.3.6

7.3.6

āha kasmāt punaratra kecidudāharaṇamantrā aśeṣataḥ paṭhyante nirucyante, keṣāñcidekadeśāḥ ? iti | ucyate --ye tāvadaśeṣāḥ paṭhyante, nirucyante ca, te vyākhyādharmopadarśenārtham | yadi punaḥ sarva eva paṭhyeran nirucyeraṃśca, atiguruśāstraṃ sampadyeta | athāpi sarveṣāmapyudāharaṇamantrāṇāmekadeśaḥ paṭhyeta nirucyeta ca tathāpi vyākhyādharmo na pradarśitaḥ syāt | tasmād vyākhyādharmopadarśanārthaṃ kecidaśeṣāḥ paṭhayante nirucyante ca, keṣāñcidekadeśāḥ, śāstrānigauravabhayāt | iti pratimantramapi sakalārddharcapādādhyayane śakyate prayojanamanveṣṭum, tadetatsamāsena brūmaḥ | yasmin yasminmantre yadyat padamekārthamanekārthamanavagatasaṃskāraṃ vā nirbrūyāti, kiñciddānyacchabdarūpamadhyāharati, anyadvāpohati, anyathā vā kaścidvipariṇāmaṃ karoti, sandigdhaṃ vā nirṇayati, tadarthameva taṃ sakalamadhīte | yasminvārddharce pāde tāvat padaṃ bhavati, yadabhimataṃ nirvaktuṃ tāvanmātramevādhīte tannirvivakṣayā | tadetadevaṃ nipuṇamanveṣṭavyaṃ sarvatra | 10 |