Shiva Purana
एवं विचारी सच्छिष्यो गुरुस्स्यात्स शिवस्स्वयम्॥ प्रपञ्चदेवतायंत्रमंत्रात्मा न हि संशयः ॥ ३६ ॥
Such a disciple becomes the preceptor Śiva himself. He attains the form of the Yantra, mantra and the cosmic deity itself.
english translation
evaM vicArI sacchiSyo gurussyAtsa zivassvayam॥ prapaJcadevatAyaMtramaMtrAtmA na hi saMzayaH ॥ 36 ॥
hk transliteration by Sanscript