What do we learn from "v'Hayah Yom Echad"?
Rashi: This will be one day of Hashem 1 .
Radak: The day will be special to Hashem.
Malbim: The day will not be divided into day and night, morning, afternoon and evening. This is only when physical luminaries serve. Then, it will be totally day.
It seems that Rashi refers to 1000 years that will follow the 6000 years of the world, like Sanhedrin 97a expounds from "Ki Elef Shanim b'Einecha k'Yom" (Tehilim 90:4). Refer to 14:7:4:1. (PF)
Why does it say "Hu Yivada la'Shem"?
Rashi: It will be known that it is preparation of His salvation.
Radak: He will be known via His mighty acts and wonders that He will do.
Malbim: It will be known that the light is totally His, and not of the sun, moon and luminaries.
What do we learn from "Lo Yom v'Lo Laylah"?
Rashi: It is not radiant light, like light of the world to come - "v'Or ha'Chamah Yihyeh Shiv'asayim k'Or [Shiv'as ha'Yamim]" (Yeshayah 30:26), and not night, which is a time of affliction, like the distress of subjugation of the kingdoms that preceded. There is no subjugation in the days of Mashi'ach!
Rashi citing Targum Yonasan: Not like the light of day, and not like the darkness of night.
Radak: It will not be totally day (respite), and not totally night (affliction).
Even Sheleimah 11(14): This hints to the seventh day of creation, on which it does not say 'va'Yhi Erev.' It is totally Shabbos [and light] - "l'Es Erev Yihyeh Ohr." It hints to the seventh millennia - the world to come.
Malbim: There will not be day and night, for these pertain to light of the sun and moon. The light then will be constant - it will neither rise nor set.
When is "l'Es Erev"?
Rashi: Before 1000 years will be completed.
Radak: At the time of the great affliction, when the city will go to Galus, "v'Yatza Hashem v'Nilcham ba'Goyim ha'Hem" (3).
Malbim: The physical sun will set, and then the primary light, of Hashem, will begin to illuminate. This is a wondrous metaphor - the influence of the luminaries will cease, and Hashem Himself will illuminate, conduct and rule with constant influence that does not change. There will be no darkness or affliction at all, nor removal of influence, which is inevitable in natural conduct via the Ma'arachah, which [is composed of matters that] ascend and decline. There will be only light, good, Shalom and success.
What light will there be?
Rashi: There will be radiance and all the good predicted for Yisrael.
