Amāvasyā-Pitṛtarpaṇa: Purūravas and the Soma-Based Ancestral Offering (अमावस्या-पितृतर्पण / सोमतर्पण-विधि)
तस्मात्सोमस्य भवति पञ्चदश्याप्रपां क्षयः / इत्येते पितरो देवाः सोमपाः सोमवर्द्धनाः
tasmātsomasya bhavati pañcadaśyāprapāṃ kṣayaḥ / ityete pitaro devāḥ somapāḥ somavarddhanāḥ
Therefore, on the fifteenth tithi Soma comes to diminution. Such are these Pitṛs, divine in nature—drinkers of Soma and increasers of Soma.