Skandapurana 6.3.159.100

6.3.159.100

prāpya cāśvayuje māsi kṛṣṇapakṣe caturdaśīm .
ahorātroṣito bhūtvā pūjayitvā maheśvaram .
mahāpātakayukto'pi mucyate nātra saṃśayaḥ .. 159.100 ..

Having reached the fourteenth day of the dark fortnight in the month of Āśvayuja, / having fasted for a day and night and worshipped Maheśvara, / even if joined with great sins, one is liberated; of this there is no doubt.