Shiva Purana
एवन्त्रिवारमुच्चार्य्य शपथं गुरुसन्निधौ । कुर्य्याद्दृढमनाश्शिष्यः शिवभक्तिसमुद्वहन्॥ ९५ ॥
Thus shall the disciple devoted to Śiva take vow in the presence of the preceptor which he shall repeat thrice with a steady mind.
english translation
evantrivAramuccAryya zapathaM gurusannidhau । kuryyAddRDhamanAzziSyaH zivabhaktisamudvahan॥ 95 ॥
hk transliteration by Sanscript