CHĀNDOGYA UPANISHAD · 3.5.1

अथ ये ऽस्योर्ध्वा रश्मयस् ता एवास्योर्ध्वा मधुनाड्यः ।
गुह्या एवादेशा मधुकृतः ।
ब्रह्मैव पुष्पं ।
ता अमृता आपः ॥

atha ye ’syordhvā raśmayas tā evāsyordhvā madhunāḍyaḥ ।
guhyā evādeśā madhukṛtaḥ ।
brahmaiva puṣpaṃ ।
tā amṛtā āpaḥ ॥

The upward rays of the sun are the honey cells above. The secret doctrines are the bees, Brahman (the Om) is the flower, the water is the nectar.

F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)