उपनयनम्Upanayana, investiture with the sacred thread
Verse 212
एवं प्रार्थयमानस्य दक्षकर्णे शिशोस्तदा । श्रावयित्वा त्रिधा तारं सर्वमन्त्रमयं शिवे । व्याहृतित्रयमुच्चार्य सावित्रीं श्रावयेद्गुरुः ॥ २१२ ॥
ēvaṁ prārthayamānasya dakṣakarṇē śiśōstadā | śrāvayitvā tridhā tāraṁ sarvamantramayaṁ śivē | vyāhṛtitrayamuccārya sāvitrīṁ śrāvayēdguruḥ || 212 ||
Translation
When he asks so, O Śivā, the guru, having made the boy hear in his right ear three times the tāra, which holds all mantras, and uttering the three vyāhṛtis, should make him hear the Sāvitrī.
Word by word
- ēvaṁ
- thus
- prārthayamānasya
- of one who asks
- dakṣa
- right
- karṇē
- in the ear
- śiśōḥ
- of the boy
- tadā
- then
- śrāvayitvā
- having made to hear
- tridhā
- three times
- tāraṁ
- the tāra (oṁ)
- sarva
- all
- mantra
- mantras
- mayaṁ
- made of
- śivē
- O Śivā
- vyāhṛti
- vyāhṛtis
- trayam
- (trayam) the three
- uccārya
- having uttered
- sāvitrīṁ
- the Sāvitrī
- śrāvayēt
- (śrāvayet) should make to hear
- guruḥ
- the guru
Meaning
Tāra is the praṇava, oṁ, called "made of all mantras" because all are contained in it. Into the right ear the guru speaks oṁ three times, then "bhūr bhuvaḥ svaḥ", then the Sāvitrī (Gāyatrī) mantra.

Commentary
Hariharānanda Bhāratī’s Sanskrit commentary, translated
"Evam" and the rest. Then, at that time, into the right ear of the boy who prays thus, the guru makes him hear three times the tāra, the praṇava (oṁ), which is made of all mantras (sarvamantramaya), the very form of all mantras, or the chief of all mantras; then, uttering the three vyāhṛtis, bhūr and the rest, he should make him hear the Sāvitrī, the Gāyatrī.