The first couple verses have a clear parallel in T212 (the earlier Udana collection) and T213 (the later Dharmapada that => Skt. Udanavarga). It goes like this in Chinese:
What’s obtained and will be obtained,
Both of these collect two dusts:
Cultivation that’s the root of illness,
And the trainee’s trainings.
Observe those who keep precepts,
The celibate brahmin practitioner,
And look on the wasting sick person:
They go to the same end.
- T213 corrects 以 to 已, which were homophones.
There’s no story attached to the verses, but there’s a straightforward commentary in T212:
The world has beings whose wrong-viewed minds proliferate greed and cravings that they can’t abandon. When they cultivate pure pursuits, they produce conceitedness from them and don’t correct themselves. This is the second end, so-called because worthies increase their attachments.
“What’s obtained and will be obtained”: Some obtain the aggregates, elements, and senses, or some won’t attain aggregates, elements, and senses.
“Both of these collect two dusts”: 1) the dust of wrong view and 2) the dust of craving. As a result, they can’t abandon the inclinations of the bonds.
“Cultivation that’s the root of illness”: Heretical disciplines cultivate the techniques of self-mortification.
“And the trainee’s trainings”: There are beings who learn those techniques of riding horses, driving chariots, and doing things that have no reason so they might provide for everything. There are those who obtain their freedom by perfect such practice. That’s what this line means.
The commentary seems kind of strained, like someone explaining something no one remembers the meaning to anymore. It goes on, but I think this might explain the parable in Pali: It’s symbolic. The two gangs are the two different wrong paths (the mortifiers and the secular people). Their wrong views lead to greed and conceitedness that can’t be abandoned. So, they are depicted as ending up fighting.
The second verse in Chinese goes in a different direction than the Pali, but it’s still talking about the brahmins and self-mortifiers vs. ordinary beings according to the commentary.