This one struck me as suspicious, mainly because of the “no one can and no one may,” which doesn’t strike me as the kind of language the Buddha used. Actually, this turns out to be an example of a translation that is so liberal that the resemblance to the original becomes tenuous.
It’s part of a slightly longer verse passage recorded in an 1894 book, Karma: A Story of Buddhist Ethics, by Paul Carus. In full the quotation is recognizable as having been derived from the Dhammapada:
By ourselves is evil done,
By ourselves we pain endure,
By ourselves we cease from wrong,
By ourselves become we pure.
No one saves us but ourselves.
No one can and no one may.
We ourselves must walk the path:
Buddhas only show the way.
Here’s a more literal translation, from Access to Insight:
165. By oneself is evil done;
by oneself is one defiled.
By oneself is evil left undone;
by oneself is one made pure.
Purity and impurity depend on oneself;
no one can purify another.
You can see a basic similarity, but “no one can and no one may” has been added to flesh out the poetry. Mostly this quote is fine. Yes, we’re responsible for our own actions. The Buddha can’t save us. We have to save ourselves. But “no one may”? That suggests that some external agency forbids others from saving us, which is not a Buddhist notion. “No one can” would have worked well as a translation on its own, but wouldn’t of course fit the rhyming scheme.
“Buddhas only show the way” seems to have been borrowed from another Dhammapada verse (276): “You yourselves must strive; the Buddhas only point the way.”
The late 19th century attempt to render the Buddha’s teaching in verse was a noble but of course an unsustainable one. In this case we’ve ended up with a note being injected (“no one may”) which simply doesn’t ring true.
PS. I’m aware that Pure Land Buddhism teaches that enlightenment is only possible through the grace of Amida Buddha, but I think it’s good to acknowledge that this approach contradicts what the Buddha seems to have taught — which is that the Buddhas only point the way, and that we must save ourselves.