Vaishnava Dharmashastra 47.3

47.3

tāṃś candrakalābhivṛddhau vardhayet, hānau hrāsayet, amāvāsyāyāṃ nāśnīyāt | eṣa cāndrāyaṇo yavamadhyaḥ ||

And let him during the moon's increase add (successively) one mouthful (every day, so as to eat one mouthful on the first day of the moon's increase, two mouthfuls on the second day, and so on; fifteen mouthfuls on the day of full moon), and during the wane of the moon let him take off one mouthful (every day, so as to eat fourteen mouthfuls on the first day of the moon's wane, thirteen mouthfuls on the second, and one mouthful on the fourteenth day of the moon's wane), and on the day of new moon let him fast entirely: thus has the barley-shaped Kândrâyana been described.