Garudapurana 1.102.5

1.102.5

kṛtaṃ tyajedāśvayuje yuñjetkālaṃ vratādinā /
pakṣe māse thavāśnīyāddantolūkhaliko bhavet //

en:He should abandon what has been collected in the month of Āśvayuja, and spend his time with religious observances and the like. / He may eat once a fortnight, or in a month, or be one who uses his teeth as a mortar;