Narada Purana — Purva Bhaga, Shloka 13
Varṇāśrama Saṁskāras, Upanayana Windows, Brahmacārin Ācāra, and Anadhyāya Prohibitions
वैश्वोपनयनं प्रोक्तं गर्भाद्द्वादशमे तथा । चतुर्विंशाब्दपर्यंतं गौणमाहुर्मनीषिणः ॥ १३ ॥
vaiśvopanayanaṃ proktaṃ garbhāddvādaśame tathā | caturviṃśābdaparyaṃtaṃ gauṇamāhurmanīṣiṇaḥ || 13 ||
「ヴァイシュヴァ・ウパナヤナ」（vaiśva‑upanayana、普遍のウパナヤナ）は、受胎から数えて第十二年に行うと説かれる。賢者たちは、第二十四年に至るまでは許容されるが、ただ「副次」（最上ではない）としてのみ可能であると宣べる。
Sanatkumara (teaching Narada in saṃskāra-dharma context)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: none
FAQs
It emphasizes saṃskāra-dharma: upanayana should be done at the proper time so Vedic study and disciplined life begin without delay; postponement weakens the intended (primary) formation.
Indirectly: timely upanayana establishes daily disciplines (like mantra-japa and regulated conduct) that later support steadiness in devotion, even though the verse itself focuses on ritual eligibility.
Ritual procedure and calendrical/age reckoning—especially counting years from conception for saṃskāra timing—reflects practical dharma-śāstra application allied to Vedanga-style precision.