Matsya Purana — Manvantaras
प्रतिमन्वन्तरं चैव श्रुतिरन्या विधीयते ऋचो यजूंषि सामानि यथावत्प्रतिदैवतम् //
pratimanvantaraṃ caiva śrutiranyā vidhīyate ṛco yajūṃṣi sāmāni yathāvatpratidaivatam //
In each Manvantara, a distinct recension of the Śruti is duly established; and the Ṛk-verses, Yajus-formulas, and Sāman-chants are arranged properly, deity by deity.
It implies cyclical cosmic time: as Manvantaras recur after vast transitions (often linked with pralaya-like resets), the revealed Veda is re-established in a fresh recension suited to that epoch.
It grounds dharma in correctly transmitted Śruti and proper ritual performance—kings and householders are expected to uphold sacrifice and worship with hymns and formulas applied in the right deity-specific order.
The significance is ritual: Ṛk, Yajus, and Sāman are to be deployed “yathāvat” and “pratidaivatam,” i.e., with precise liturgical mapping of mantra-types to the appropriate deity in worship and sacrifice.