What do we learn from "u'Fduyei Hashem Yeshuvun u'Va'u Tziyon b'Rinah"?
Sanhedrin 110b: This teaches that Dor ha'Midbar will come to the world to come.
Malbim: Hashem redeemed them from all their afflictions; they will return from Galil and come to Tziyon singing, unlike those who came to Tziyon from Galus Bavel in sadness. They suffered many evils, like it says in Ezra and Nechemyah. Eventually, the sadness departed and they had Simchah.
What is "Simchas Olam [Al Rosham]"?
Shabbos 88a: When Yisrael said 'Na'aseh' before 'Nishma', everyone received two crowns. After Chet ha'Egel, they were removed. In the future, Hashem will return them to Yisrael.
Rashi: Simchah that they had already, when they left Egypt "va'Hashem Holech Lifneihem Yomam" (Shemos 13:21).
Radak: This is a metaphor - they will go upright with their head held high b'Simchah.
Malbim: An eternal Simchah will be seen on their heads. There will be no grief or Galus afterwards, unlike in Bayis Sheni.
To where do Yagon and Anachah flee?
Rashi: From them.
Malbim: It is as if Sason v'Simchah chase them. Sason is exposed, and Simchah is in the heart. Similarly, Anachah is exposed, and Yagon is in the heart.
