Sreemad Bhagawatha Mahatmyam – Chapter Twenty One

सताहेन शुतं चैततसवरथा मुिकदायकम ।
सनकादैः पुरा पोकं नारदाय दयापरःै ॥२१॥

Sapthaahena srutham chaithath sarvatthaa mukthidhaayakam
Sanakaadhyaih puraa proktham Naaradhaaya dhayaaparaih.

It is only necessary to listen to this great sacred text simply just only for seven days for you to secure supreme mental bliss.  The most merciful and kindest Sanakas once in the past praised and sung the glories of Lord Sri Maha Vishnu and explained the benefits of it to Narada.