Rabbi Roodyn

ו) הִגִּידוּ הַשָּׁמַיִם צִדְקוֹ וְרָאוּ כָל הָעַמִּים כְּבוֹדוֹ:

The heavens told His righteousness, and all the earth saw His glory.

The Malbim explains that through the events of the previous pesukim everyone will see that the heavenly spheres do not just operate according to the set laws of nature, rather they act in accordance with Hashem’s will. Therefore the heavens will tell of Hashems tzedek, righteousness in all that He does through them to reward and punish man in accordance with His deeds in the fullest way possible.

This will be the ultimate refutation to the Sabeans and those like them who say that the heavenly bodies can be manipulated by man to suit the needs of mankind. Such a belief system has nothing to do with tzedek, righteousness, it just depends on man’s ability to ‘play the system’. When Hashem’s providence becomes manifest, it will be evident to all that it operates according to His perfect judgement.

In addition, since the Sabeans believe in many forces that act independently of each other on different parts of the word, the result being that each nation will be treated  differently. The pasuk therefore says that all the earth will see His glory, clearly implying that there is One force that runs the world.