Narada Purana — Purva Bhaga, Shloka 30
Dīkṣā, Mantra-Types, Mantra-Doṣas, and Qualifications of Ācārya–Śiṣya
स सार्णो दृश्यते यस्तु स मंत्रो दग्धसंज्ञकः । अस्रं द्वाभ्यां त्रिभिः षड्भिरष्टाभिर्दृश्यतेऽक्षरेः ॥ ३० ॥
sa sārṇo dṛśyate yastu sa maṃtro dagdhasaṃjñakaḥ | asraṃ dvābhyāṃ tribhiḥ ṣaḍbhiraṣṭābhirdṛśyate'kṣareḥ || 30 ||
「sārṇa」（鼻音・visargaに似た付加記号、または添えられた音声標）を伴うマントラは、「dagdha（焼けた／欠損の）」マントラと呼ばれる。「asra」と名づけられるマントラの形相は、二・三・六・八の音節（akṣara）によって成るときに現れる。
Sanatkumara (teaching Narada in a Vedanga/Mantra-śāstra context)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: adbhuta
FAQs
It emphasizes that mantra-efficacy depends on correct phonetics and structure; certain phonetic marks and syllabic formations are treated as technical indicators for judging a mantra’s fitness in ritual use.
Even in devotion, the Purana upholds disciplined practice: bhakti expressed through japa and ritual should follow proper śikṣā (pronunciation) and mantra-lakṣaṇa so that worship is performed without technical faults.
Śikṣā and mantra-śāstra: it classifies mantras by observable phonetic marks (like sārṇa) and by akṣara-count patterns (2/3/6/8), a practical diagnostic used in correct recitation and ritual application.