How does Shamayim Mesaper (tell) Hashem's honor?
Rashi: It is like he proceeds to explain (the sun rises each morning like a Chasan leaving his Chupah - verse 6).
Radak #1: From the wonders and great deeds that man sees in Shamayim, he tells Hashem's honor.
Radak #2: Through the trajectories and orbits of the [celestial bodies] Shamayim and the Raki'a in the proper order, Hashem's honor is seen. This is telling - "ha'Shole'ach Imraso Aretz Ad Meherah Yarutz Devaro" (147:15).
Radak: The Rambam (Moreh ha'Nevuchim 2:5) and philosophers say that the [celestial] spheres are living intellectual beings that serve Hashem. They give a great praise to Him.
Malbim: "Shamayim" includes all Heavenly causes in the world of spheres. Raki'a is a particular name for where the vapors rise, and there it becomes rain or hail. The limit of the land reaches until there. It is proper for breathing for all living beings. Above it is the border of Shamayim; living beings cannot exist there. So say the Rambam and those who hold like him. Kavod is owed to Hashem because He created everything, and is the cause of all created beings. Shamayim tells this. All who see this great building and the luminaries in it, they know that there is one Creator who arranged everything with His ability and Chachmah.
How is the Raki'a Magid His works?
Rashi: The stars and Mazalos, which are Hashem's works, are there - "va'Yiten Osam Elokim bi'Rki'a ha'Shamayim" (Bereishis 1:17). From there, they tell His honor.
Radak: This is a repetition of Shamayim telling His honor. Shamayim is Raki'a - "va'Yiten Osam Elokim bi'Rki'a ha'Shamayim" (Bereishis 1:17), according to the opinion that it discusses the spheres. Ibn Ezra says that Raki'a is the air.
Malbim: Shamayim teaches that there is one Creator, but not that He still engages in creation and renews the creation every day and conducts the world. This we know from the Raki'a, from the wonders of rain and Hashgachah found in it. He still acts, prepares rain and makes grass sprout on mountains.
Malbim citing Kesuvos 5a: Who tells the acts of Tzadikim? The Raki'a, i.e. [via] rain. It comes via Tefilah of Tzadikim, and Hashem brings it in its time, every place according to its need. Hagadah is something new, and relevant to the hearer. The Raki'a constantly informs new acts of Hashem needed for people. Shamayim tells only what was (Hashem created everything in six days).
