Shiva Purana
आवाह्य पूजयेच्छंभुं षोडशैरुपचारकैः । स्वयमैश्वर्यमाप्नोति ज्ञानमभ्यासतो भवेत् ३८ ।
The devotee can invoke the lord in a natural immobile thing—a rock or a stump—or an engraved picture and worship Śiva by the sixteen Upacāras (services and homage). He will attain supreme power of the lord and by practice gain knowledge.
english translation
AvAhya pUjayecchaMbhuM SoDazairupacArakaiH । svayamaizvaryamApnoti jJAnamabhyAsato bhavet 38 ।
hk transliteration by Sanscript