9.
The Second Discourse on Ascetics and Brahmins
122.
He was dwelling at Sāvatthī, etc.
"There are, monks, these four elements.
What are the four?
The solid element, the liquid element, the heat element, the air element.
Whatever ascetics or brahmins, monks, who do not understand as it really is the origin, passing away, gratification, danger, and escape of these four elements, etc.
They understand, etc.
Having realised by direct knowledge themselves, having attained, they dwell."
The ninth.