Shiva Purana
पुण्यारण्ये तथारामे सहस्रगुणमुच्यते ॥ अयुतं पर्वते पुण्ये नद्यां लक्षमुदाहृतम् ॥ ४४ ॥
In a holy forest or park it is thousand times more. On a holy mountain it is ten thousand times more. On the banks of a river it is hundred thousand times more.
english translation
puNyAraNye tathArAme sahasraguNamucyate ॥ ayutaM parvate puNye nadyAM lakSamudAhRtam ॥ 44 ॥
hk transliteration by Sanscript