Today I was searching for a half-remembered baraita to the effect that if all Israel were to keep the Law for a single day, the Messiah would come — but I couldn’t call to mind enough of the exact words for G***** to be of any help. Finally I came up with some unattributed quotations of the principle (shame on you colleagues whom I will allow to remain anonymous), but Margaret spotted one iteration of the principle:
Said R Levi, “If Israel would keep a single Sabbath in the proper way, forthwith the son of David will come. [y. Taanit, 1:1, toward the end]
Just before that, a slightly different alternative:
R. Aha in the name of R. Tanhum b. R. Hiyya, “If Israel repents for one day, forthwith the son of David will come. [again, y. Taanit 1:1]
By then I’d forgotten why I was looking for the passage, but that didn’t stop me from being distracted from the work I needed to do — oh, no! So I also came up with
It is taught in another baraita that Rabbi Eliezer says: If the Jewish people repent they are redeemed, as it is stated: “Return, wayward children, I will heal your iniquities” (Jeremiah 3:22). [b. Sanhedrin, 97b]. (By the way, Sanhedrin 97b is a wonderful illustration of how richly controverted, and how variously imagined, the coming of the Messiah was imagined in Judaic antiquity — contra the countless commentators who treat Judaic culture as a homogeneous unanimity.)
None of these reflects what I thought I remembered (which is actually, as I discovered almost exactly what several NT scholars have said in print, without citing a source), but they’re close enough for me to move on… for now.