Shiva Purana

siva.sh/siva-purana/kotirudra-samhita/13/44

तदोंनमः शिवायेति श्रीशब्द पूर्वकाय च ।। वारान्षोडश संकल्पपूजां कुर्यादयं बटुः।। ४४ ।।

sanskrit

Then the brahmin boy performed the Saṃkalpapūjā (worship by mental conception) sixteen times with the five-syllabled mantra with the word Śrī prefixed to Śiva.

english translation

tadoMnamaH zivAyeti zrIzabda pUrvakAya ca || vArAnSoDaza saMkalpapUjAM kuryAdayaM baTuH|| 44 ||

hk transliteration by Sanscript