Narada Purana — Purva Bhaga, Shloka 23
Dīkṣā, Mantra-Types, Mantra-Doṣas, and Qualifications of Ācārya–Śiṣya
तारवर्मत्रया लक्ष्मीरेवं हीनस्तु यो मनुः । शक्तिहीनः स विज्ञेयश्चिरकालफलप्रदः ॥ २३ ॥
tāravarmatrayā lakṣmīrevaṃ hīnastu yo manuḥ | śaktihīnaḥ sa vijñeyaścirakālaphalapradaḥ || 23 ||
如是，若“manu”缺少三重护甲（tāra-varma），当知其力薄弱；不现吉祥天女拉克什米之临在，其果亦须久时方得。
Sanatkumara (in instruction to Narada)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: none
FAQs
It teaches that mantra-phala depends on correct mantric structure and protection; a deficient mantra is considered śakti-hīna and yields results only slowly, emphasizing precision and discipline in sādhanā.
It implies that devotion must be accompanied by proper vidhi (method): sincere bhakti aligned with correct mantra-prayoga brings auspicious grace (symbolized by Lakṣmī) more effectively than careless or incomplete practice.
A technical principle of mantra-śāstra used within Vedāṅga-style disciplines: mantras require correct components (often taught as coverings/kavaca/nyāsa-like protections); otherwise their śakti is weakened and the promised phala is delayed.