Shiva Purana

siva.sh/siva-purana/saturda-samhita/7/1

।। नन्दिकेश्वर उवाच ।। तत्र गत्वा मुनेऽहं वै स्थित्वैकान्तस्थले सुधीः ।। अतपं तप उग्रं सन्मुनीनामपि दुष्करम् ।। १।।

sanskrit

Nandīśvara said:— O sage, after going there and staying in an isolated place with a steady mind I performed a severe penance very difficult even for good sages.

english translation

|| nandikezvara uvAca || tatra gatvA mune'haM vai sthitvaikAntasthale sudhIH || atapaM tapa ugraM sanmunInAmapi duSkaram || 1||

hk transliteration by Sanscript