I posit that one crucial element of the gemoro in kessubos (sholosh shevuos) is missing from all of the talk and commentaries on this post. The fact is that the sholosh shevuos were said by Yirmijohu Hanovih and – even if they were valid ad the time- the Jews returned to Eretz Yisroel for the second Bayis! Why wouldn’t those shevuos be valid then if ,indeed, they were “halocho”? (R’Zvi Hirsch Kalisher zz’l makes that speicific point).The standard answer that you hear is that they returned “al pi novih”. But there is no evidence of any divrei nevuoh on that. Ezra and Nehemia were not neviim and returned to Eretz Yisroel because they received permission from the emperor! not that different than today! For the ones who will try to catch me, I know that, according to some shittos, Malachi is Ezra but it does not detract from my questions.
