Jaiminīya (Talavakāra) Brāhmaṇa 2-8.308.p1

2-8.308.p1

pṛṣṭhya eva ṣaḍaho'tha yatsaptamamahastatsarvameva caturviṃśaṃ pañcaviṃśaṃ mahāvrataṃ

There is the pṛṣṭhya six-day period itself; then as to what the seventh day is: that whole [day] is twenty-fourfold; the Mahāvrata is twenty-fivefold;