What does this Mizmor discuss?
Rashi: Refer to 80:1:3:1.
Radak: It discusses this Galus.
Malbim: Bnei Asaf composed it when Ezra and Nechemyah returned from Galus and wanted to build the Heichal, and their enemies wanted to fight with them and stop them. They were impoverished; it compares their return from Bavel to their return from Egypt. It has three parts. (a) In part one he prays to save them from their afflicters who want to fight against them. (b) Hashem should widen their borders with serenity and income. (c) He should gather their dispersed and help them to build the Beis ha'Mikdash. Each part concludes "Hashivenu v'Ha'er Panecha v'Niva'she'a." Corresponding to these three requests are (in verse 2) three descriptions of the earlier era 1 .
What is "El Shoshanim"?
Rashi: It is to Yisrael.
What is "Edus"?
Rashi: It is testimony; It hints to three exiles, and he prayed for them - "Hashivenu", "v'Ha'er Panecha" and "v'Niva'she'a" (verse 4). It hints to future afflictions that will come in the days of Beis Yehu from Malchei Aram - "Ki Ibdam Melech Aram va'Ysimem ke'Afar Ladush" (Melachim II, 13:7).
Radak #1: Some say that it is the beauty of a matter, like "v'Adis Edi 1 " (Yechezkel 23:40).
Radak #2: The beginning of the Mizmorim refer to musical matters; they are not known to us.