What do we learn from "Ra'ucha Yachilu Harim"?
Rashi: The mountains of Nachalei Arnon clung to each other.
Radak: Mountains are a Mashal for the kings of Kena'an. They melted and feared due to Yisrael. They saw the wonders that You did with Yisrael in the Midbar and with the kings of the Emori. It says "Ra'ucha 1 ", for a clear hearing is like seeing. The same applies to "va'Yar Yakov Ki Yesh Shever b'Mitzrayim" (Bereishis 42:1).
Radak citing Targum Yonasan: When You revealed Yourself on Har Sinai, they saw Your honor, and the mountains shook.
Malbim: Now it discusses how the water rose to go above the mountains and flood the world, to take vengeance against nations, until the mountains (Yesod he'Afar) will fear Yesod ha'Mayim, which overpowers it.
Even though they did not see those wonders ? they only heard about them. (PF)
Why does it say "Zerem Mayim Avar"?
Rashi: When they passed through the Yarden, the water was divided. Downstream [from Yisrael], it flowed normally; upstream of Yisrael, the water piled up.
Radak: The flow of water in the Yarden passed until Yam ha'Aravah ? it ceased and finished.
How did the depth give its voice?
Rashi: Residents of the land praised Him.
Radak: This was when the Yarden's water was split.
Malbim: The verse depicts that the Tehom commands the flooding water [to rise]. Where Yisrael pass, the land overpowers the rivers and dries them. For Yisrael's afflicters, it is opposite ? the water overpowers the land!
What is the significance of "Rom Yadehu Nasa"?
Rashi: The legions of Shamayim admitted to Him.
Radak: The water that descends from upstream, it piled up. It was very high, for the Yarden was overflowing its banks and there was much water ? the Tehom lifted its hand high. .
