Amāvasyā-Pitṛtarpaṇa: Purūravas and the Soma-Based Ancestral Offering (अमावस्या-पितृतर्पण / सोमतर्पण-विधि)
संपूर्ममण्डलः श्रीमांश्चन्द्रमा उपरज्यते / यस्मादा दाप्यायते सोमः पञ्चदश्यां तु पूर्णिमा
saṃpūrmamaṇḍalaḥ śrīmāṃścandramā uparajyate / yasmādā dāpyāyate somaḥ pañcadaśyāṃ tu pūrṇimā
The glorious moon shines forth with its disk made whole; for on the fifteenth tithi Soma is nourished into fullness—therefore that day is Pūrṇimā, the full moon.