What fence did He make around me?
Rashi: He made a wall around me to incarcerate me.
Palgei Mayim: Hashem became so much like an enemy, as if He built a wall to block me from the path of Teshuvah, lest I leave my sins and afflictions 1 .
Hashem sent Nevi'im to tell them to repent! However, when the punishment came, it was very hard to repent. Sometimes 'they do not enable him to repent', e.g. one who caused Rabim to sin (Avos 5:18, Yuma 8:9). Melech Menasheh caused Rabim to sin, and he repented! They do not enable him to repent, i.e. it is very hard for him, but it is possible. (PF)
Why does it need to say also "v'Lo Etzei"?
Rashi: He stationed around me camps and troops of ambushers.
Ri Kara: Had Hashem only put me in darkness, I could not leave due to the darkness. He also made a wall around me - all the more so I cannot leave.
What is the meaning of "Hichbid Nechashti"?
Rashi: He made heavy fetters for my feet 1 so I cannot walk. Ri Kara - even if there was light, and there was no wall around me, I could not leave due to the fetters.
Palgei Mayim: There are four metals 2 - gold, silver, Nechoshes (copper) and lead. Ya'aros Devash (2:6) explains that they correspond to man's actions. Copper represents actions that depend on the Yetzer ha'Ra, e.g. eating and marital relations, which are tied to the acts of the Nachash (snake). Here it says that Hashem made Nechashti (my Yetzer ha'Ra) heavy, to become Tamei via deeds that depend on it.
Rid: This is like "va'Ya'asruhu ba'Nechushtayim" (Shoftim 16:21).
He cannot mean that these are the only four. Bamidbar 31:22 lists these four, and also iron and tin! (PF)
