What is the meaning of "Ovrei b'Emek ha'Bacha"?
Rashi, Radak (8, citing Eruvin 19a): Those who transgress Your creed. They are in the Omek (depth) of Gehinom, and cry and moan.
Radak: This is a metaphor for Chachamim. "Bacha" is like "Nivchei Yam" (Iyov 38:16), a place of a spring. They pass in the depth of springs of Chachmah. They make it a spring for Talmidim and those who come after them. They will drink water of Chachmah to know Hashem.
Radak (8): If this Mizmor discusses Olei Regalim, this is a valley of trees called Tusim. They grow where there is no water. Therefore when Olei Regalim passed there, they dug for water, until the entire valley became like a spring.
Malbim: These paths in their hearts are "Ovrei b'Emek ha'Bacha." Bavel is a valley, and full of springs and trees; it is called "Nachal ha'Aravim" (Yeshayah 15:7). The verse mentions Becha'im (springs) in place of Aravim, for it also alludes to crying; they sat on the willows and cried.
What is the "Mayan"?
Rashi: It is [like a spring of] their tears.
Why does it say "Gam Brachos Yateh Moreh"?
Rashi: They bless and thank His name, and say 'You judged us properly; Your judgment is Emes.' Brachos wrapped us - He taught us to go in the good path, and we did not listen.
Radak: The one who teaches them the way of Chachmah, Brachos will clothe him.
Radak (8) #1: We read "Brachos" like Brechos (pools of water). The same applies to "Havah Li Vrachah" (Shoftim 1:15). The Brechah is a cavity built with stones and plaster, and rainwater enters it. The verse teaches that there was water for Olei Regalim from the springs and Brechos on the roads. They were full, for the rain 'clothed' them with water. "Moreh" is like "Yoreh u'Malkosh" (Devarim 11:14). They did not lack anything when they ascended for the Regel.
Radak (8) #2: Brachos will clothe one who taught us to go in a straight path, but we did not heed Hashem's voice - therefore we are in this valley.
Malbim: In their hearts were paths going to Elokim in Tziyon. It made their hearts like a spring of influence and Brachah. Via great trust in Hashem, they were able to teach others and fill their hearts with hope that they will return to the fortress.
