Śatapatha Brāhmaṇa ("of a hundred paths") 11.5.4.2

11.5.4.2

athāsya hastaṃ gṛhṇāti indrasya brahmacāryasyagnirācāryastavāhamācāryastavāsāvityete vai śreṣṭhe baliṣṭhe devate etābhyāmevainaṃ śreṣṭhābhyām baliṣṭhābhyāṃ devatābhyām paridadāti tathā hāsya brahmacārī na kāṃ canārtimārcati na sa yaevaṃ veda

He then takes his (right) hand with, 'Indra's disciple thou art; Agni is thy teacher, I am thy teacher, O N.N.!'--now these are two most high and most powerful deities: it is to these two most high and most powerful deities he commits him; and thus his disciple suffers no harm of any kind, nor does he who knows this.