Matsya Purana — Ritual Bathing
दर्भपाणिस्तु विधिना आचान्तः प्रयतः शुचिः चतुर्हस्तसमायुक्तं चतुरस्रं समन्ततः प्रकल्प्यावाहयेद् गङ्गाम् एभिर्मन्त्रैर्विचक्षणः //
darbhapāṇistu vidhinā ācāntaḥ prayataḥ śuciḥ caturhastasamāyuktaṃ caturasraṃ samantataḥ prakalpyāvāhayed gaṅgām ebhirmantrairvicakṣaṇaḥ //
Holding kuśa-grass in his hand, and having duly performed ācamana, disciplined and pure, the adept should prepare on all sides a square measuring four hastas, and then, with these mantras, skillfully invoke the presence of the River-Goddess Gaṅgā.
This verse is not about pralaya; it focuses on ritual purity and the formal invocation (āvāhana) of Gaṅgā through ācamana, darbha, and a prepared square ritual space.
It outlines a standard dharmic procedure for a disciplined practitioner—relevant to householders and rulers alike—emphasizing cleanliness (śuci), self-restraint (prayata), and correct performance of rites (vidhi) before sacred acts like bathing or worship.
Ritually, it prescribes preparing a caturasra (square) maṇḍala of four hastas as the designated sacred space for mantra-based invocation—an example of precise spatial measurement used in Purāṇic ritual practice (often aligned with Vastu-style geometric ordering).