यदेव ते कश्चिदब्रवीत्तच्छृणवामेति ।अब्रवीन्मे बर्कुर्वार्ष्णः ।चक्षुर्वै ब्रह्मेति ।यथा मातृमान् पितृमानाचार्यवान् ब्रूयात्तथा तद्वार्ष्णोऽब्रवीच्चक्षुर्वै ब्रह्मेति ।अपश्यतो हि किं स्यादिति ।अब्रवीत्तु ते तस्यायतनं प्रतिष्ठाम् ।न मेऽब्रवीदिति ।एकपाद्वा एतत्सम्राडिति ।स वै नो ब्रूहि याज्ञवल्क्य ।चक्षुरेवायतनमाकाशः प्रतिष्ठा ।सत्यमित्येतदुपासीत ।का सत्यता याज्ञवल्क्य ।चक्षुरेव सम्राडिति होवाच ।चक्षुषा वै सम्राट्पश्यन्तमाहुरद्राक्षीरिति ।स आहाद्राक्षमिति तत्सत्यं भवति ।चक्षुर्वै सम्राट्परमं ब्रह्म ।नैनं चक्षुर्जहाति ।सर्वाण्येनं भूतान्यभिक्षरन्ति ।देवो भूत्वा देवानप्येति ।य एवं विद्वानेतदुपास्ते ।हस्त्यृषभं सहस्रं ददामीति होवाच जनको वैदेहः ।स होवाच याज्ञवल्क्यः पिता मेऽमन्यत नाननुशिष्य हरेतेति ॥बृह. ४,१.४ ॥
In plain words
"Let me hear what anyone has told thee." "Barku Vārṣṇa told me, 'The eye indeed is Brahman.'" "As one who had a mother, a father and a teacher might say, so did Vārṣṇa say that the eye indeed is Brahman; for what would one have who could not see? But did he tell thee its dwelling and its support?" "He did not tell me." "Then this is a thing of one foot only, your majesty." "Then do thou tell us, Yājñavalkya." "The eye is its dwelling and space its support. Let a man worship it as the real." "What is realness, Yājñavalkya?" "The eye itself, your majesty," he said. "For when men say to one who has seen with the eye, 'Didst thou see?' and he says, 'I saw,' that is real. The eye, your majesty, is the highest Brahman. The eye does not leave him, all beings flow toward him, and becoming a god he goes to the gods, who worships it thus knowing." "I give thee a thousand cows with a bull like an elephant," said Janaka of Videha. Yājñavalkya said, "My father held that one should not take a gift without having taught."
The commentators
Bṛhadāraṇyakopaniṣadbhāṣyam· bhāṣya
यदेव ते कश्चित् बर्कुरिति नामतः वृष्णस्यापत्यं वार्ष्णः ; चक्षुर्वै ब्रह्मेति- आदित्यो देवता चक्षुषि । उपनिषत्- स- त्यम् ; यस्मात् श्रोत्रेण श्रुतमनृतमपि स्यात् , न तु चक्षुषा दृष्टम् , तस्माद्वै, सम्राट्, पश्यन्तमाहुः- अद्राक्षीस्त्वं हस्ति- नमिति, स चेत् अद्राक्षमित्याह, तत्सत्यमेव भवति ; यस्त्वन्यो ब्रूयात्- अहमश्रौषमिति, तद्व्यभिचरति ; यत्तु चक्षुषा दृष्टं तत् अव्यभिचारित्वात् सत्यमेव भवति ॥
In plain words
Now, about the one who taught you this -- his name was Bṛku, son of Vṛṣṇi, called Vārṣṇa -- and he said 'the eye, truly, is Brahman'; the sun is the deity living in the eye. Its name is Truth, and here's why: what you hear can turn out false, but what you see with your own eyes can't. That's why, Your Majesty, when someone has seen something, people ask, 'Did you really see the elephant?' and if he says 'I saw it,' that's simply true. But if someone else only says 'I heard about it,' that can go wrong. What the eye actually sees, though, never fails -- so it's always true.
Close to the Sanskrit
Now, the one who told you this -- Bṛku by name, offspring of Vṛṣṇi, [called] Vārṣṇa -- [said] 'the eye, indeed, is Brahman'; the sun is the deity in the eye. [Its] designation is 'truth'; because what is heard by the ear may even be false, but not what is seen by the eye. Therefore, indeed, O emperor, they ask one who is seeing -- 'did you see the elephant?' -- if he says 'I saw it', that indeed becomes true; but if another person were to say 'I heard it', that is liable to error; whereas what is seen by the eye, because of its infallibility, indeed becomes true.