looking for citation, pīti and sukha of 4 jhānas compared to dying of thirst, seeing water in distance, and drinking it

There's an excellent simile in the Theravada non canonical literature explaining the difference between piti and sukha in the first 3 jhanas, reminiscent of the lotus pond in this sutta MN 40. (citation?) As I remember it: - Piti = you're in a desert, dying of thirst, as you're approaching oasis/pond, you realize there's water in the distance, that you're not going to die, and you're going to drink that water soon. The thrill and excitement of that is piti. - sukha = you've arrived at the oasis/pond, now you're drinking the water. The pleasure from actually drinking the water is sukha. Three questions: 1. what is the citation of that piti sukha simile for the 4 jhanas from? 2. might this sutta, MN 40, be what inspired that simile for jhana piti/sukha differentiation? Should the words piti sukha appear in MN 40 lotus pond, but got lost in transmission? 3. What does the MN 40 lotus pond simile mean on its own terms, just for this sutta? What are the 4 directions referring to? MN 40 excerpt here: [MN 40: what is the meaning of the lotus pond simile?](https://notesonthedhamma.blogspot.com/2019/09/mn-40-what-is-meaning-of-lotus-pond.html)