Monks, there are other things which are very deep (profound), very hard to understand, very difficult to perceive, so holy and sacred, unreached by means of mind, so subtle, that they are only to be understood and experienced by the wise. These things were perceived clearly, seen clearly and were discarded by the Tathagata, and by this act based on the truth that people praise and revered Tathagatha. What are those things?

Brahmajala Sutra (Theravada) - Digha Nikaya