Shiva Purana

siva.sh/siva-purana/kotirudra-samhita/3/14

ध्यायति स्म परं ज्योतिरात्मस्थमात्मना च सः ।। अत्रिर्मुनिवरो ज्ञानी शंकरं निर्विकारकम् ।। १४ ।।

sanskrit

Atri, the great sage of perfect knowledge, meditated on Śiva devoid of aberrations, the great splendour stationed in the soul, through his own soul.

english translation

dhyAyati sma paraM jyotirAtmasthamAtmanA ca saH || atrirmunivaro jJAnI zaMkaraM nirvikArakam || 14 ||

hk transliteration by Sanscript