Shiva Purana

siva.sh/siva-purana/saturda-samhita/9/68

विश्वेश्वरेऽपि ये भक्ता नो भक्ताः कालभैरवे ।। ते लभन्ते महादुःखं काश्यां चैव विशेषतः ।। ६८ ।।

sanskrit

The devotees of lord Śiva, who do not show devotion for Kālabhairava, attain great sorrow and especially so at Kāśī.

english translation

vizvezvare'pi ye bhaktA no bhaktAH kAlabhairave || te labhante mahAduHkhaM kAzyAM caiva vizeSataH || 68 ||

hk transliteration by Sanscript