Canonical Reference: Paticchanna Sutta (Open Discourse) Verified Source

“Three things shine brightly and cannot be long hidden: the sun, the moon, and the truth.”

Canonical Pali Original: Tīṇimāni, bhikkhave, vivaṭāni virocanti, no paṭicchannāni: candamaṇḍalaṃ, sūriyamaṇḍalaṃ, tathāgatappavedito dhammavinayo.

— Gautam Buddha
The Awakened One, Founder of Dhamma
Historical Setting & Context:

Pali Canon: Anguttara Nikaya 3.129 where the Buddha states that the moon, the sun, and the Dhamma (Truth) shine openly when unveiled.