What are "Chitzecha"?
Rashi: The illnesses, which are like arrows.
Malbim: They are arrows that penetrate into the depths of the soul [and weaken it] via despair and worry.
What is the meaning of "Nichasu"?
Rashi: They were cast [at me]. Nichasu refers to drawing the bow, for via it, the arrows are shot. Similarly, it should say Arik Ta'ari; it says '"Arik Charbi" (Shemos 15:9), because when one takes the sword, he empties the case. It similarly says above "v'Nichasah Keshes Nechushah" (18:35). The Nun is not from the root; if it were, it would say Nenachasu. Rather, [it is of conjugation,] and sometimes it is omitted, like the Nun in Nagaf, Nashach, Nadar
What is the meaning of "va'Tinchas Alai Yadecha"?
Rashi: This explains what cast Your arrows at me - Your hand. "Va'Tinchas" is an expression of descent. The Nun is from the root. Radak - the Targum of "va'Yered" (Bereishis 12:10) is v'Nachas.
Malbim: These are revealed bodily afflictions. They are [external, like] via a fist.
