What is "b'Shuv Hashem Es Shiv'as Tziyon"?
Rashi: It is returning to Tziyon from Galus Bavel.
Radak #1: "Shuv" is resting - "Shuvah Hashem Rivevos Alfei Yisrael" (Bamidbar 10:36), "v'Shav Hashem Elokecha Es Shevuscha v'Richamecha" (Devarim 30:3).
Radak #2: Shuv refers to Teshuvah; it is Po'el Yotzei (it acts on others); Hashem will cause Bnei Tziyon to return to Hashem.
How will they be like dreamers?
Shocher Tov: Choni ha'Mag'il was always astounded - can one sleep for 70 years (the length of Galus Bavel) in a dream?! It occurred to him, that he slept for 70 years.
Radak citing his father: Like a dream flies away (when one awakens), so the affliction of Galus will be in our eyes due to the great Simchah when we return to our land.
Radak citing Ibn Ezra: When Hashem returns the exile of Yisrael, they will say that one sees such a wonder only in a dream.
Malbim: It depicts Yisrael's hope that Hashem fulfill His promise via the Nevi'im to return their exile, like one who has a prophetic dream. He sees the future like the present, as if it is reality, and rejoices over it like one who rejoices over a current good - "Hekitzosi va'Er'eh u'Shnasi Arvah Li" (Yirmeyah 31:25). The only difference between a Navi's vision and seeing a matter carried out, is that the Navi's Simchah is only in his heart, and he cannot express it via laughter and song. Regarding the return to Tziyon, we already were like dreamers who saw it in a vision, and when Hashem will return it, in action.
