Matsya Purana — Yuga Durations
विद्याद्द्वादशसाहस्रीं युगाख्यां पूर्वनिर्मिताम् एवं सहस्रपर्यन्तं तदहर्ब्राह्ममुच्यते //
vidyāddvādaśasāhasrīṃ yugākhyāṃ pūrvanirmitām evaṃ sahasraparyantaṃ tadaharbrāhmamucyate //
One should understand the Yuga—previously established—as consisting of twelve thousand (years, in divine reckoning). In this manner, up to a thousand (such Yugas), that total is called a ‘day of Brahmā’.
It defines Brahmā’s ‘day’ as a thousand Yuga-cycles; in Purāṇic cosmology, such vast time-units frame periodic creation and dissolution processes that occur on cosmic scales.
By teaching long-range cosmic time, it encourages rulers and householders to act with dharma and restraint, recognizing that power, wealth, and lifespan are brief within Brahmā’s immense cycles.
No direct Vāstu or temple rule is stated; indirectly, it supports ritual calendrics by grounding sacred observances in Purāṇic time-measures (yuga and larger cycles).