Shiva Purana
इति ध्यात्वा च संपूज्य पार्थिवं लिंगमुत्तमम् । जपेत्पंचाक्षरं मंत्रं गुरुदत्तं यथाविधि ५३ ।
After the meditation and worship of the excellent earthly image he shall duly perform the Japa of the five-syllabled mantra taught by the preceptor.
english translation
iti dhyAtvA ca saMpUjya pArthivaM liMgamuttamam । japetpaMcAkSaraM maMtraM gurudattaM yathAvidhi 53 ।
hk transliteration by Sanscript