Shiva Purana
प्रणवं त्रिःप्रकारं तु ततस्तस्यार्थमादिशेत् ॥ षड्विधार्थं परिज्ञानसहितं गुरुसत्तमः ॥ ६३॥
Then one should instruct the three types of oṁkāra for its purpose. The best of teachers with knowledge of the sixfold meaning.
english translation
praNavaM triHprakAraM tu tatastasyArthamAdizet ॥ SaDvidhArthaM parijJAnasahitaM gurusattamaH ॥ 63॥
hk transliteration by Sanscript