Matsya Purana — Catalogue of the Eighteen Puranas
मानवस्य प्रसङ्गेन कल्पस्य मुनिसत्तमाः चतुर्विंशत्सहस्राणि तत्पुराणमिहोच्यते //
mānavasya prasaṅgena kalpasya munisattamāḥ caturviṃśatsahasrāṇi tatpurāṇamihocyate //
O best of sages, in connection with Manu and this kalpa, this Purāṇa is here declared to consist of twenty-four thousand (verses).
It does not describe pralaya directly; it frames the Purāṇa as being told in the context of Manu and the kalpa, i.e., the cosmic-cycle setting in which pralaya and recreation narratives are typically situated.
Indirectly: by stating the Purāṇa’s scope and its Manu–kalpa context, it signals that the text’s teachings (including rājadharma and gṛhastha-dharma) are embedded within Manu-centered cosmic and ethical order.
No specific Vāstu or ritual rule is stated; the verse serves as a cataloging note that helps locate and authenticate the Purāṇa’s contents—within which Vāstuvidyā and ritual procedures are taught elsewhere.