5.
The Discourse on What is Conducive to True Knowledge
35.
"Monks, there are these six mental states conducive to true knowledge.
Which six?
Perception of impermanence, perception of suffering in what is impermanent, perception of non-self in what is suffering, perception of abandoning, perception of dispassion, perception of cessation -
these, monks, are the six mental states conducive to true knowledge."
The fifth.