Yāska's Nirukta 16.3

16.3

ataḥ paraṃ samprasāraṇacintā varttiṣyate, tadarthamidamārabhyate,-"tadyatra svarādanantarāntasthāntardhātu bhavati tad dviprakṛtīnāṃ sthānamiti pradiśanti" | samprasāryaprakṛtayaścāsamprasāryaprakṛtayaścobhayaprakṛtayaśca dhātavaḥ | tatraivaṃ satyubhayaprakṛtiṣu svaśāstraviṣayagataṃ yadvaktavyaṃ tat idamucyata iti paryupayuktastacchabdaḥ | āha-idameva tāvaducyatāmubhayaprakṛtīnāṃ kiṃ lakṣaṇam iti ? ucyate-yatra yasmin dhātau svarāt akārādeḥ anantarā anantarhitā anyena vyañjanena, parā vā pūrvā antasthā yaralavānāmanyatamo varṇaḥ antardhātu dhātumadhye bhavati | kiṃ tatra ? tat etadeva lakṣaṇaṃ dhāturūpaṃ hi dviprakṛtīnāṃ dvikhabhāvānāṃ śabdānāṃ sthānam āśraya iti evamācāryāḥ pradiśanti pravibhāgenopadiśanti | tadyathā-'yaja devapūjāsaṅgatikaraṇadāneṣu (bhṛ0 u0 )-iti | atra dve śabdaprakṛtī bhavataḥ | samprasāraṇapakṣe tāvatiṣṭavān, iṣṭiḥ, iṣṭvā, etāḥ śabdaprakṛtayo bhavanti | asamprasāraṇapakṣe punaḥ-yaṣṭā, yaṣṭuṃ, yaṣṭavyamityetāḥ |