Shiva Purana
व्याख्यातत्वञ्च कर्म्मादिगुर्वासनपरिग्रहम् ॥ अनुगृह्य गुरुस्तस्मै शिष्याय शिवरूपिणे ॥ ४८ ॥
and the explained nature of the rituals and the attachment of the seat of the teacher. The teacher showed mercy to his disciple in the form of Lord Śiva.
english translation
vyAkhyAtatvaJca karmmAdigurvAsanaparigraham ॥ anugRhya gurustasmai ziSyAya zivarUpiNe ॥ 48 ॥
hk transliteration by Sanscript