my pranams.
1) Hari-bhakti-vilāsa (1.125) says that the dvādaśākṣara can be chanted with mudrā and yantras. Also Hari-bhakti-vilāsa (12.341) says that someone initiated in the dvādaśākṣara should ideally obtain it along with the mudrā, yantras etc to be considered a proper arcaka. Mudrās are not Vedic but Tantrik as far as far as I have heard (i will be happy to be contradicted on this point).
2) In the dig-darśinī commentary to hari-bhakti-vilāsa (4.173) it is said that some vaishnavas apply the final part of the tilaka to the top of the head by chanting dvādaśākṣara. It then says — "atrāpi sat-sampradāyācāra eva gatir iti dik" — every sat-sampradāya may have its own understanding regarding such mantras and their practical applications.
3) According to the Śrīmad-bhāgavatam (11.5.28) — yajanti veda-tantrābhyām — even in Dvāpara yuga, people were not sticking strictly only to Vedic mantras but were understanding the practicalities through tantra. What then to speak of Kali-yuga? The Śrīmad-bhāgavatam (11.5.31) says — nānā-tantra-vidhānena kalāv api tathā śṛṇu — In Kali yuga, Vishnu is worshiped mainly through tantras. Sridhar Swami says in the commentary — nānā-tantra-vidhāneneti kalau tantra-mārgasya prādhānyaṁ darśayati — by the phrase "nānā tantra-vidhānena", the predominance of the path of tantras in the age of Kali is expressed.
So even if the mantra has originated from a Purāṇa or an Upaniṣad, it is treated as a tāntrika mantra as far as practical application is concerned.
sādhu-caraṇa-rajo'bhilāṣī,
hari parshad das.
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