upākarmaṇi cotsarge trirātraṃ kṣepaṇaṃ smṛtam / aṣṭakāsu tv ahorātram ṛtvantāsu ca rātriṣu //
On (the occasion of) the Upakarman and (of) the Vedotsarga an omission (of the Veda-study) for three days has been prescribed, but on the Ashtakas and on the last nights of the seasons for a day and a night.