For reasons I wish to source the quote "Do not be daunted by the enormity of the world's grief. Do justly, now. Love mercy, now. Walk humbly, now. You are not obligated to complete the work, but neither are you free to abandon it." It is universally attributed to "The Talmud". This is about as helpful as referring to a quote as being from "The Bible" or "The Tanakh" instead of the more precise "Isaiah 49:15" or even just "Book of Isaiah".
The closest I've found is
the last sentence, differently phrased, in paragraph 16 here, and obviously the difference in phrasing can be attributed to translator choices. But you'll observe that the preceding sentences at the link are
nothing like the preceding sentences in the quote...
Okay,
apparently the middle bit is a paraphrase of
Micah 6:8.
But where did the first bit come from? I'm only finding it in context of the rest of the quote, and nobody has a more precise attribution than "The Talmud".