Matsya Purana — Cosmography of Śākadvīpa and Successive Dvīpas: Mountains
पवित्रा तृतीया विज्ञेया वितृष्णापि च या पुनः चतुर्थी ह्लादिनीत्युक्ता चन्द्रभा इति च स्मृता //
pavitrā tṛtīyā vijñeyā vitṛṣṇāpi ca yā punaḥ caturthī hlādinītyuktā candrabhā iti ca smṛtā //
Know the third as Pavitrā (the Purifying one) and also as Vitṛṣṇā (the Thirstless/Desireless). Again, the fourth is said to be Hlādinī (the Gladdening one) and is also remembered as Candrabhā (Moon-lustrous).
This verse does not discuss Pralaya; it classifies lunar days (tithis) by auspicious epithets, emphasizing ritual timekeeping rather than cosmology.
It supports dharmic duty through correct observance of time: a householder (and by extension a king overseeing public rites) should align vows, worship, and purificatory acts with appropriate tithis, here highlighting the purifying third day and the gladdening fourth day.
Ritually, it provides tithi-epithets used when scheduling vratas and pūjā: tṛtīyā is linked with purification and freedom from craving, while caturthī is linked with joy and moonlike radiance—useful for selecting auspicious timings in Matsya Purana ritual practice.