Manava Dharmashastra 2.106

2.106

naityake nāsty anadhyāyo brahmasattraṃ hi tat smṛtam
brahmāhutihutaṃ puṇyam anadhyāyavaṣaṭkṛtam //

There are no forbidden days for the daily recitation, since that is declared to be a Brahmasattra (an everlasting sacrifice offered to Brahman); at that the Veda takes the place of the burnt oblations, and it is meritorious (even), when (natural phenomena, requiring) a cessation of the Veda-study, take the place of the exclamation Vashat.