Listening to Shiva Purana once reduces sins to ashes

व्यासोपदेशश्रीशिवमहापुराणमाहात्म्यवर्णनं नामैकचत्वारिंशोऽध्यायः

Sage Vyasa's advice and greatness of Shree Shiva MahaPurana description - Chapter 41

व्यास उवाच |

Sage Vyasa said (to the sages)

एतच्छ्रुत्वा ह्येकवारं भवेत्पापं हि भस्मसात् |
अभक्तो भक्तिमाप्नोति भक्तो भक्तिसमृद्धिभाक् || 45 ||
पुनः श्रुते च सद्भक्तिर्मुक्तिस्स्याच्च श्रुतेः पुनः |
तस्मात्पुनःपुनश्चैव श्रोतव्यं हि मुमुक्षुभिः || 46 ||

On listening this (Shiva Purana) just once, sin reduces to ashes, a non-devotee obtains devotion, a devotee bears rich (a lot more) devotion.
And on listening again, (one gets) good devotion, and on listening again (a third time), liberation is achieved. Therefore, those who want liberation should really listen (to this Shiva Purana) again and again.