THE DECREE AGAINST A NAILED SANDAL
Who are Shelufei ha'Gezeirah?
Rashi: They were people evading a [royal] decree.
Rav Elyashiv citing Rashi (Yevamos 116b): This was the end of a decree.
Why were people allowed to enter, but not to leave?
Rashi: One can see that no one is looking when he enters; he cannot do so before leaving. Perhaps the enemy will see him leave, and realize that they are hiding there.
Why did they think that someone had left?
Rashi: His footprints were seen. Since the sandal was reversed, it seemed that he went in the opposite direction (he left).
Rav Elyashiv: The footprints were seen because the sandal had wide nails. Since the nails led to the fatalities, they decreed about a nailed sandal.
What Kol did they heard above the cave?
Tosfos: They heard the sound of a nailed sandal.
Do the Amora'im argue about the episode?
Rav Elyashiv citing Sefas Emes: No. All three episodes occurred. There are consequences of this; see my Ha'aros on Beitzah 15a. In the last two episodes, they heard a Kol; nailed sandals are noisy. They decreed about nailed sandals, for they led to the fatalities.
What is the answer 'the episode occurred on Shabbos'?
Rashi: They forbade only like the episode.
Rav Elyashiv: The decree is not lest another episode like this occur. That is very unlikely! (NOTE: If it occurred three times, it could occur again! - PF) Rather, it is due to Oneg Shabbos. When one sees a nailed sandal, he remembers the episodes [and is sad]. So says a Hagahah in Melaches Shlomo on our Mishnah, and the end of Tosfos DH v'Lo (one may not send a nailed sandal on Yom Tov. The Heter to send a Kli she'Melachto l'Isur on Yom Tov is for Simchas Yom Tov. Since it led to fatalities, there is no Simchas Yom Tov through it.) The Makshan asked, it should be forbidden even during the week! He thought that the decree is lest similar cases occur. The Tartzan answered, it is due to Oneg Shabbos. Even though the Tana said 'one may not go out with a nailed sandal', it is forbidden even in Reshus ha'Yachid. Perhaps it is permitted in Reshus ha'Rabim, for the episodes were in Reshus ha'Yachid.