Brihadaranyaka Upanishad 2.5.9

2.5.9

ayam̐ stanayitnuḥ sarveṣāṃ bhūtānāṃ madhvasya stanayitnoḥsarvāṇi bhutāni madhu yaścāyamasminstanayitnau tejomayo'mṛtamayaḥ puuruṣoyaścāyamadhyātmam̐ śābdaḥ sauvarastejomayo'bhṛtamayaḥ puruṣo'yameva sa yo'yamātmedamamṛtamidaṃ brahmedam̐ sarvam

This thunder is the honey of all beings, and all beings are the honey of this thunder. Likewise this bright, immortal person in this thunder, and that bright, immortal person existing as sound and voice in the body (both are madhu). He indeed is the same as that Self, that Immortal, that Brahman, that All.