Garudapurana 1.133.3

1.133.3

(ityaśokāṣṭamīvratam) /
brahmovāca /
śuklāṣṭamyāmāśvayuje uttarāṣāḍhayā yutā /
sā mahānavamītyuktā snānadānādi cākṣayam //

(Thus the Aśokāṣṭamī observance.) / Brahmā said: / When the bright eighth lunar day in Āśvayuja is conjoined with Uttarāṣāḍhā, / that is spoken of as Mahānavamī, and ablution, donation, and the like become imperishable.