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य आवृणोति आपूरयति अमृतं पूर्णानन्दं ब्रह्म आत्मत्वेन संप्रयच्छन् तस्मै आचार्याय न द्रुह्येत् द्रोहं नाचरेत् ।तथा च श्रुतिः—‘यस्य देवे परा भक्तिर्यथा देवे तथा गुरौ ।तस्यैते कथिता ह्यर्थाः प्रकाशन्ते महात्मनः’ ।तथा चापस्तम्बः—‘तस्मै न द्रुह्येत्कदाचन ।स हि विद्यातस्तं जनयति’ इति ।
In plain words
The teacher is the one who fills you — fills you with the deathless Brahman, which is bliss without a gap, and hands it over not as something to look at but as your own Self. Toward such a teacher, never any malice; never a single hostile act. As the śruti says: for the one whose devotion to God is total, and whose devotion to the teacher matches it exactly, these teachings that have been spoken to him stop being words and begin to shine. Āpastamba says the same: never injure him — through knowledge, he is the one who gave you birth.
Close to the Sanskrit
He who āvṛṇoti — that is, fills up — bestowing, as one's very Self, the deathless Brahman which is full bliss: to that teacher one should not bear malice, that is, one should not commit any act of injury. And so the śruti says: 'He whose devotion to God is supreme, and as toward God so toward the teacher — to him, the great-souled one, these declared meanings shine forth.' And so too Āpastamba: 'To him one should never do injury; for he begets him through knowledge.'