Matsyapurana 141.28

141.28

evamāpyāyate somaḥ kṣayite ca punaḥ punaḥ
samṛddhirevaṃ somasya pakṣayoḥ śuklakṛṣṇayoḥ //

The phases of the Moon that wax in course of the bright fortnight fed by Suṣumṇâ wane during the dark fortnight In this way the Moon continues to wax and wane, consequently, the full moon is called the receptacle of nectar He is luminous with the fifteen nectar giving phases. He is, therefore, called Pitṛimân—26 28