Who are "Rechokim"?
Radak #1: They are Goyim from distant lands.
Radak #2: They are Yisrael, who are scattered in Galus in a far land.
Malbim: These are Yisrael, who are now distant and did not return in Bayis Sheni.
Will they build the Heichal?
Radak: They will volunteer [money or materials] to build the Bayis. Perhaps this was in the days of Hordus, in the great Mikdash that he built.
Malbim: Yes, if all [who remained in Bavel] will be aroused and come.
How will you know that Hashem sent me to you?
Malbim: All the prophecies for the future that Hashem sent me to tell you, they will be fulfilled.
What do we learn from "v'Hayah Im Shamo'a..."?
Rashi: This will happened (they will come from afar and build the Mikdash) if you will heed...
Radak: All that I promise you will be if you will heed Hashem's voice. Malbim - then, the promises will not fulfilled immediately. The far one will return, and the crown will return to its former status.
