Brihadaranyaka Upanishad 2.5.8

2.5.8

iyaṃ vidyutsarveṣāṃ bhūtānāṃ madhvasyai vidyutaḥsarvāṇi bhṛtāni madhu yaścāyamasyāṃ vidyuti tejomayo'mṛtamayaḥ puruṣo yaścāyamadhyātmaṃ taijasastejomayo'mṛtamayaḥ puruṣo'yameva sa yo'yamātmedamamṛtamidaṃbrahmedam̐ sarvam

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