Reference for Taanit 57:11

ובשניה מנלן דתניא מגלגלין זכות ליום זכאי וחובה ליום חייב

And this is what R'Johanan meant when he said: Had I been alive in that generation I should have fixed [the mourning] for the tenth, because the greater part of the Temple was burnt thereon. How will the Rabbis then [explain the contradiction]? - The beginning of any misfortune is of greater moment. AND [THE TEMPLE WAS DESTROYED] THE SECOND TIME.

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