Brihadaranyaka Upanishad 4.1.5

4.1.5

yadeva te kaścida-bravīttacchṛṇavāmetyabravīnme gardabhīvipīto bhāradvājaḥ śrotraṃ vai brahmeti yathā mātṛmānpitṛmānācāryavānbrūyāttathā tadbhāradvājo'bravīcchrotraṃ vai brahmetyaśṛṇvato hi kim̐ syādityabravīttu te tasyāyatanaṃ pratiṣṭhāṃ na me'bravīdityekapādvā etatsamrāḍiti sa vai no brūhi yājñavalkya śrotramevāyatanamākāśaḥ pratiṣṭhānanta ityenadupāsīta kānantatā yājñavalkya diśa eva samrāḍitihovāca tasmādvai samrāḍapi yāṃ kāṃ ca diśaṃ gacchati naivāsyā antaṃ gacchatyanantā hi diśo diśo vai samrāṭśrotram̐ śrotraṃ vai samrāṭparamaṃ brahma nainam̐ śrotraṃ jahāni sarvāṇyenaṃ bhūtānyabhikṣaranti devo bhūtvā devānapyeti ya evaṃ vidvānetadupāste hastyṛṣabham̐ sahasraṃ dadāmīti hovāca janako vaidehaḥ sa hovāca yājñavalkyaḥ pitā me'manyata nānanuśiṣya hareteti

'Let me hear whatever anyone may have told you.' Gardabhivipīta, of the line of Bharadwâja, has told me that the ear (the quarters) is Brahman.' 'As one who has a mother, father and teacher should say, so has the descendant of Bharadwâja said this—that the ear is Brahman, for what can a person have who cannot hear? But did he tell you about its abode and support?' 'No, he did not.' 'This Brahman is only one-footed, O Emperor.' 'Then you tell us, Yâjnavalkya.' 'The ear is its abode, and the ether (Undifferentiated) its support. It should be meditated upon as infinite.' 'What is infinity, Yâjnavalkya?' 'The quarters themselves, O Emperor,' said Yâjnavalkya, 'therefore, O Emperor, to whatever direction one may go, one never reaches its end. (Hence) the quarters are infinite. The quarters, O Emperor, are the ear, and the ear, O Emperor, is the Supreme Brahman. The ear never leaves him who, knowing thus, meditates upon it, all beings eagerly come to him, and being a god, he attains the gods.' 'I give you a thousand cows with a bull like an elephant,' said Emperor Janaka. Yājñavalkya replied, 'My father was of opinion that one should not accept (wealth) from a disciple without fully insructing him.'