Matsya Purana — Bhīma-Dvādaśī
तस्मात्त्वं सत्त्वमालम्ब्य भीमसेन विमत्सरः कुरु व्रतमिदं सम्यक् स्नेहात्तव मयेरितम् //
tasmāttvaṃ sattvamālambya bhīmasena vimatsaraḥ kuru vratamidaṃ samyak snehāttava mayeritam //
Therefore, O Bhīmasena, taking refuge in sattva (purity and steadiness) and free from envy, perform this vow properly—this instruction has been spoken by me out of affection for you.
This verse does not address pralaya or cosmology; it focuses on ethical preparation—cultivating sattva and freedom from envy—as the inner basis for successfully undertaking a religious vow.
It frames vrata as a disciplined duty: one should undertake observances with sattvic steadiness and without jealousy (matsara). For rulers and householders alike, the teaching emphasizes inner purity and correct procedure as prerequisites for dharmic action.
The ritual takeaway is procedural: the vow must be performed “samyak” (properly and correctly). No Vastu or temple-architecture rule is stated, but the verse underscores correct observance as essential to ritual efficacy.