Shiva Purana
नातप्ततपसो यांति ब्रह्मलोकं कदाचन ॥ नातप्ततपसां प्राप्यश्शंकरः परमेश्वरः ॥ ४३॥
Those who have never performed penance (tapas) do not attain Brahmaloka; lord Śiva is not accessible to those who have never performed penance.
english translation
nAtaptatapaso yAMti brahmalokaM kadAcana ॥ nAtaptatapasAM prApyazzaMkaraH paramezvaraH ॥ 43॥
hk transliteration by Sanscript