Narada Purana — Purva Bhaga, Shloka 8
Nirukta, Phonetic Variants, and Vedic Dhātu–Svara Taxonomy
सुप्तिङुपग्रहलिंगनराणां कालहलूचूस्वरकर्तृयडां च । व्यत्ययमिच्छति शास्रकृदेषां सोऽपि च सिद्ध्यति बाहुलकेन ॥ ८ ॥
suptiṅupagrahaliṃganarāṇāṃ kālahalūcūsvarakartṛyaḍāṃ ca | vyatyayamicchati śāsrakṛdeṣāṃ so'pi ca siddhyati bāhulakena || 8 ||
对于名词格尾（suP）、动词词尾（tiṅ）、前缀（upagraha）、性别与人称/施事，以及时态（kāla）、字母ha、lu、cū、音调（svara）、施事者（kartṛ）与字母yaḍ等——若语法论典作者意在令其相互倒置或替换，则此亦可凭通行用法（bāhulaka）而成立。
Sanatkumara (teaching Narada in a Vedanga/śāstra context)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: none
FAQs
It frames śāstra as both rule-governed and usage-aware: disciplined learning (especially Vedāṅgas like Vyākaraṇa and Śikṣā) supports clarity in Vedic study, which in turn aids right understanding on the path of dharma and mokṣa.
Indirectly: accurate speech, chanting, and comprehension depend on grammar and accent; such correctness strengthens mantra-recitation and scriptural hearing (śravaṇa), which are foundational supports for sustained Viṣṇu-bhakti even when the verse itself is technical.
Vyākaraṇa and Śikṣā: it notes that grammatical authorities may allow substitutions and irregular forms, and that these can be accepted when backed by prevalent usage (bāhulaka), including matters of endings (suP/tiṅ) and Vedic accent (svara).