Which episode is the Torah hinting at (See Ramban)?
Rashi and Ramban #1 (citing the Sifri): The episode with Chananyah ben Eizor, 1 who prophesied that the Keilim of the Beis Hamikdash that had been taken to Bavel with Yechonyah Melech Yehudah would soon be returned, and Yirmiyah retorted 2 that, not only would those Keilim not be returned, but the Keilim that were still in the Beis-Hamikdash would be taken to Bavel as well.
Ramban: The main objective of the Pasuk is to teach us that if the prophecy does not come true, then the 'Navi' is Chayav Misah.
Seforno: It is hinting at the episode with Eliyahu on Har ha'Carmel 3 and to that of Yehoshua, who ordered the people to go round the walls of Yerushalayim on Shabbos, and the Kohanim to stand in the River Yarden until the people had crossed, each of whom gave Si'man before instigating the new temporary Mitzvah. 4
Why does the Torah not refer to the equally obvious question 'How will we know to follow the Navi in the event that his prophecy does materialize'?