Matsya Purana — Pratiśukra Rite and the Worship of Śukra
पीतपुष्पाम्बरयुतं कृत्वा स्नात्वाथ सर्षपैः पलाशाश्वत्थयोगेन पञ्चगव्यजलेन च //
pītapuṣpāmbarayutaṃ kṛtvā snātvātha sarṣapaiḥ palāśāśvatthayogena pañcagavyajalena ca //
Having adorned oneself with yellow flowers and yellow garments, one should then bathe using mustard seeds, together with the sanctifying presence of palāśa and aśvattha, and also with water mixed with pañcagavya.
It does not address pralaya directly; it focuses on ritual purification—how a practitioner prepares through sanctifying bath substances before undertaking a religious act.
It reflects the householder/kingly duty of maintaining śauca (ritual cleanliness) before vows, worship, or public rites—using culturally sanctioned purifiers like mustard and pañcagavya.
The significance is ritual (not architectural): mustard seeds, palāśa, aśvattha, and pañcagavya are prescribed purifiers; yellow attire/flowers signal auspicious, sattvic preparation for vrata and worship.