Brihadaranyaka Upanishad 2.63

तदेतदृचाभ्यनूक्तम् — अयमग्निर्वैश्वानरो योऽयमन्तः पुरुषे | येनेदमन्नं पच्यते यदिदमद्यते | तस्यैष घोषो भवति यमेतत्कर्णावपिधाय शृणोति | स यदोत्क्रमिष्यन्भवति नैनं घोषं शृणोति ॥

tad etad richabhyanooktam — ayam agnir vaishvanaro yo'yam antah purushe | yenedam annam pachyate yad idam adyate | tasyaisha ghosho bhavati yam etat karnavapi dhaya shrinoti | sa yad utkramishyan bhavati nainam ghosham shrinoti ||

This is expressed in the Rik verse: 'This is the Vaishvanara fire that is within a person, by which the food that is eaten is cooked (digested). It is its sound that one hears by covering the ears thus. When one is about to depart this life, one no longer hears this sound.'

यह ऋचा में अभिव्यक्त है: 'यह वैश्वानर अग्नि जो पुरुष के भीतर है — जिससे यह अन्न पचता है जो खाया जाता है — यह रुद्र है। इसके लिए ये प्राण धूम की तरह उठते हैं।'