Shiva Purana
यत्रयत्र यदा शंभुर्भक्त्या भक्तैश्च संस्मृतः ॥ तत्रतत्रावतीर्याथ कार्यं कृत्वा स्थितस्तदा ॥ १६ ॥
Śiva incarnates in those places wherever he is devoutly remembered by the devotees. After carrying out their task he stations himself there.
english translation
yatrayatra yadA zaMbhurbhaktyA bhaktaizca saMsmRtaH ॥ tatratatrAvatIryAtha kAryaM kRtvA sthitastadA ॥ 16 ॥
hk transliteration by Sanscript