Bhashya
यदेव ते कश्चित् बर्कुरिति नामतः वृष्णस्यापत्यं वार्ष्णः ;चक्षुर्वै ब्रह्मेति- आदित्यो देवता चक्षुषि ।उपनिषत्- स-त्यम् ; यस्मात् श्रोत्रेण श्रुतमनृतमपि स्यात् , न तु चक्षुषादृष्टम् , तस्माद्वै, सम्राट्, पश्यन्तमाहुः- अद्राक्षीस्त्वं हस्ति-नमिति, स चेत् अद्राक्षमित्याह, तत्सत्यमेव भवति ;यस्त्वन्यो ब्रूयात्- अहमश्रौषमिति, तद्व्यभिचरति ; यत्तुचक्षुषा 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.