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 ||
名詞語尾（suP）、動詞語尾（tiṅ）、接頭要素（upagraha）、性（liṅga）と人称・行為者、さらに時制（kāla）、ha・lu・cūの字、音調（svara）、行為主体（kartṛ）、およびyaḍの字などにおいて—文法シャーストラの作者がそれらの転換・交替を意図するなら、そのこともまた慣用（bāhulaka）によって成立する。
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).