Why does it say "Yehalelu Es Shem Hashem"? Verse 5 already said so!
Radak: All creations in the lower world will praise Him. I.e. those with Da'as will praise for all the creations.
Why does it say "Ki Nisgav Shmo Levado"? It did not say so above regarding upper beings!
Radak #1: Also upper beings are elevated. Even so, lower beings say that only Hashem is Nisgav, for He is over the upper beings; He created them. There is no Nisgav among them; their Gedolim do not endure [forever], so they do not get haughty about their grandeur 1 , for in a short time they will die, and their grandeur will cease.
Radak #2: This is a Tefilah for the future, when the redeemer will come. Then all will admit that only Hashem is elevated, and their grandeur is folly - "Einei Gavhus Adam Shafal v'Shach Rom Anashim v'Nisgav Hashem Levado ba'Yom ha'Hu" (Yeshayah 2:11).
Malbim: These will praise because His name alone is exalted. Even though they have choice, Hashem's name is exalted to them. Via this they ascend the ladder to approach Hashem.
Midrash ha'Gadol (Devarim 7:7, cited in Rashi there): Pharaoh said "Mi Hashem Asher Eshma b'Kolo" (Shemos 5:2), Nevuchadnetzar, said "Adameh l'Elyon" (Yeshayah 14:14), Sancheriv said "Mi b'Chol Elohei ha'Aratzos... " (ibid., 36:20), and Chiram said "El Ani Moshav Elokim Yashavti" (Yechezkel 28:2)! Perhaps Radak means that most earthly beings do not get haughty. (PF)
What is the meaning of "Hodo Al Eretz v'Shamayim"?
Radak: All creations above and below exist via His strength, and His beauty is on them via a chain of causes.
Malbim: Initially, Hashem's glory descended from Shamayim to the land. Now it returns to its supreme source.
