Matsya Purana — Cosmography of Śākadvīpa and Successive Dvīpas: Mountains
अपां विदारणाच्चैव मन्दरः स निगद्यते तत्र रत्नान्यनेकानि स्वयं रक्षति वासवः //
apāṃ vidāraṇāccaiva mandaraḥ sa nigadyate tatra ratnānyanekāni svayaṃ rakṣati vāsavaḥ //
Because it also “splits the waters,” it is called Mandara. There, many kinds of precious jewels are found, and Vāsava (Indra) himself protects them.
Indirectly, it reflects Puranic cosmography: primordial waters and the motif of ‘cleaving the waters’ point to a world-structure where mountains and divine realms stand amid or above cosmic waters, a background often invoked in Pralaya narratives.
By depicting Indra as a guardian of treasures, the verse mirrors the rājadharma ideal that wealth and valuable resources should be protected through rightful guardianship, not exploited—an ethical template for rulers and householders managing prosperity.
No direct Vāstu rule is stated, but the verse supports a common Purāṇic idea used in temple and tīrtha contexts: sacred landscapes (mountains, waters) are divinely protected and thus ritually potent—guiding site-selection reverence in later Vāstu/kshetra traditions.