Matsya Purana — Vrata-Ṣaṣṭhī: The Sixty Sacred Vows
पक्षोपवासी यो दद्याद् विप्राय कपिलाद्वयम् ब्रह्मलोकमवाप्नोति देवासुरसुपूजितम् कल्पान्ते राजराजः स्यात् प्रभाव्रतमिदं स्मृतम् //
pakṣopavāsī yo dadyād viprāya kapilādvayam brahmalokamavāpnoti devāsurasupūjitam kalpānte rājarājaḥ syāt prabhāvratamidaṃ smṛtam //
Whoever, observing a fortnight-long fast, gives a brāhmaṇa a pair of tawny (kapilā) cows attains the world of Brahmā, revered by gods and demons alike; and at the end of the kalpa he becomes a king of kings. This is remembered as the Prabhā-vrata.
It uses cosmic-time language—“kalpānte” (end of a kalpa)—to frame karmic results across vast cycles, implying that merits from vrata and dāna can bear fruit even at the close of a cosmic age.
It promotes the householder/kingly virtue of dāna (charitable giving), specifically supporting Brahmins and ritual order; the promised fruit—becoming “rājarāja” (king of kings)—links ethical generosity with ideal rulership in the Matsya Purana’s dharma framework.
Ritually, it prescribes a vrata: fasting for a fortnight and gifting two kapilā cows to a Brahmin; it does not discuss Vāstu or temple architecture in this verse, but it is a clear dana–vrata procedure with stated spiritual and worldly rewards.