Vishnu Dharmottara Puran

 जपतो हरिनामानिस्थानेशतगुणाधिक:। आत्मानञ्चपुनात्युच्चैर्जपन्श्रोतृन्पुनातपच॥

Translation: Chanting of Hari-nama loudly is hundred times better than Japa. By Japa one purifies oneself, while by loud chanting one purifies the self & the hearers.

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