Shiva Purana

siva.sh/siva-purana/saturda-samhita/9/63

कृष्णाष्टम्यान्तु मार्गस्य मासस्य परमेश्वरः ।। आविर्बभूव सल्लीलो भैरवात्मा सताम्प्रियः ।। ६३।।

sanskrit

It was on the eighth day in the dark half of the month of Mārgaśīrṣa that lord Śiva, the favourite of the good and indulging in auspicious sports, manifested himself in the form of Bhairava.

english translation

kRSNASTamyAntu mArgasya mAsasya paramezvaraH || AvirbabhUva sallIlo bhairavAtmA satAmpriyaH || 63||

hk transliteration by Sanscript