What is "Maskil El Dal"?
Rashi, Radak: He investigates [needs of] the sick. "Dal" is like "Madu'a Atah Kachah Dal" (Shmuel II, 13:4) regarding Amnon.
Malbim: He uses his intellect to investigate the needs of the Dal. From the survival of the sick, and how Hashem guards him from mishaps, Hashem's Hashgachah on the weak and downtrodden is seen clearly. The rich, strong and tyrants are saved via nature, due to their wealth and strength - "Hon Ashir Kiryas Uzo" (Mishlei 10:15). The Dal lacks these means; only Hashgachah saves him.
What is "Yom Ra'ah"?
Rashi: It is Gehinom.
Radak: It is when his illness worsens, and he is close to death.
Malbim: It is hardships based on the time, e.g. snow in winter, and burning heat in summer, and [danger] when the new Tekufah begins.
What is the tense of "Yemaltehu Hashem"?
Radak: Refer to 41:3:1:1-3.
