Shiva Purana
हस्तं निधाय शिरसि शिष्यस्य स गुरुर्वदेत् ॥ त्रिवारं प्रणवं दक्षकर्णे ऋष्यादिसंयुतम् ॥ ८७ ॥
Putting his hand on the head of the disciple the preceptor shall utter the Praṇava thrice into the right ear of the disciple along with the names of the sage etc.
english translation
hastaM nidhAya zirasi ziSyasya sa gururvadet ॥ trivAraM praNavaM dakSakarNe RSyAdisaMyutam ॥ 87 ॥
hk transliteration by Sanscript