Shiva Purana
असौ हि परमेशानस्स्वयंज्योतिस्सनातनः ॥ आनन्दरूपा तस्यैषा शक्तिर्नागन्तुकी शिवा ॥ ३५ ॥
The great lord, is self-luminous and eternal. Śivā is his Śakti in the form of Bliss, not a chance occurrence.
english translation
asau hi paramezAnassvayaMjyotissanAtanaH ॥ AnandarUpA tasyaiSA zaktirnAgantukI zivA ॥ 35 ॥
hk transliteration by Sanscript