I did expect to find a discussion about this. But I didn’t. I collected these suttas with the nice system of search suttacentral has. I did say to improve but I have to say the search has made my dream come true. Let’s you find exactly what you looking for in term of words and doctrine. Thank you
The nine apertures:
“O body, you have nine streams
that are flowing all the time.”
“There are nine apertures on a person’s body, and they are like nine wounds caused by a spear. The nine apertures are ill-smelling and impure.”
Another translation says
For it has been said by the Blessed One:
“Covered with clammy skin, an impure thing and foul,
Nine-apertured, it oozes, like a sore.”
Step-by-step Stopping
“Monks, there are these nine step-by-step stoppings. Which nine?
“Whatever would ooze out from it would be an uncleanliness oozing out, a stench oozing out, a disgust oozing out. Whatever would be discharged from it would be an uncleanliness discharging, a stench discharging, a disgust discharging. For that reason, you should become disenchanted with this body.”
Here says 4 door for aggregates and mind probably as the nine door. The jhana states is nothing but nature of the mind which need to be let go of. The nine openings producing stench.
“Having four wheels and nine doors,
Filled up and bound with greed,
Born from a bog, O great hero!
How does one escape from it?”
“Having cut the thong and the strap,
Having cut off evil desire and greed,
Having drawn out craving with its root:
Thus one escapes from it.”
“Mendicants, there are these nine progressive cessations. What nine?