Tittha Sutta

[1] Udana is one of the oldest texts in the Pali Canon of Theravāda Buddhism.

Udāna consists of eight chapters ( cradle ) with ten conversations or sutras each, ie.

Each sutra consists of a long story or parable and a short concluding udāna, or exclamation, from the Buddha.

[3][4] The scripture is about some monks (Bhikkhus) who hear some ascetic Hindus in lively argumentation about whether the world is eternal or not, infinite or not, whether the soul is separate from the body or not.

The moral of the matter is that it is a waste of time and energy to determine what it is you are experiencing, as this will necessarily be different.

It is therefore occasionally attributed to both Christian sources and the American poet John Godfrey Saxe.