Matsya Purana — Kṛṣṇāṣṭamī Vrata: Monthly Śiva-Names
द्विजानामुदकुम्भांश्च पञ्चरत्नसमन्वितान् गावः कृष्णाः सुवर्णं च वासांसि विविधानि च अशक्तस्तु पुनर्दद्याद् गामेकामपि शक्तितः //
dvijānāmudakumbhāṃśca pañcaratnasamanvitān gāvaḥ kṛṣṇāḥ suvarṇaṃ ca vāsāṃsi vividhāni ca aśaktastu punardadyād gāmekāmapi śaktitaḥ //
One should give to the twice-born (Brāhmaṇas) water-pots (udakumbha) furnished with the five gems (pañcaratna), along with black cows, gold, and various kinds of garments. But if one is unable, then according to one’s capacity one should at least give even a single cow.
This verse does not discuss pralaya; it focuses on dāna-dharma—recommended gifts and the principle of giving according to capacity.
It frames charity as a core duty: ideally give valuable ritual items (water-pot with pañcaratna, cows, gold, garments), but if resources are limited, one should still perform at least minimal charity—such as gifting one cow—according to one’s means.
The ritual significance is the prescribed dāna items—especially the udakumbha (water-pot) and pañcaratna—used in auspicious gifting; it is not a Vāstu/temple-architecture rule but a ritual charity guideline.