Pensée juive sur Les Psaumes 135:1

Moses’s error had also been that he had believed in the supremacy of natural law as dictated by the intellect. He had to be taught that this was not so. In the word az, referring to the past, he wished to atone for his erstwhile error. The end of the Midrash quoted at the outset, namely that the righteous can achieve atonement with the very thing that constituted their error, expresses the same thought as what had prompted Moses to commence the shirah, song with the word az. This song is divided into five sections, each representing a distinct concept. 1) The need to give thanks to the Lord. 2) Acknowledging the mastery G-d displays over His creation.(verses 3-6) 3) The reputation G-d acquired due to His personal intervention in the fate of individuals as well as nations, plus the fact that despite His involvement in minutiae, His stature does not suffer from a decline in image, (verse 7-13) 4) Proof that everything that happened was intentional, not accidental, (verses 14-16) 5) The declaration that G-d’s power is eternal and will extend into all future eras, i.e. "the Lord will rule forever more."