 चोदितो रामवाक्येन विश्वामित्रो महामुनि:।वृद्धिं जन्म च गङ्गाया वक्तुमेवोपचक्रमे।। 
  Prompted by Ramas words, maharshi Viswamitra started narrating the account of the birth and progress of river Ganga.  