Why is the episode with Na'aman written here?
Rashi: The Navi arranges the miracles done through Elisha.
What is the meaning of "Ki Vo Nasan Hashem Teshu'ah la'Aram"?
Radak citing Targum Yonasan: Hashem made Aram win via him. Rashi (from Yalkut Shimoni 222): He shot an arrow without intent, and killed Achav.
Radak: citing Pirkei d'R. Eliezer (16): When Lavan gathered everyone [in his city] and made a feast [for Yakov's marriage to his daughter], Hashem said, you did Chesed with Yakov; I will give your reward to your children, so Resha'im will not have reward in the world to come - "Ki Vo Nasan 1 Hashem Teshu'ah la'Aram."
Radal (on the Midrash): It should have said Asah. "Nasan" teaches that Hashem paid them. (If one did Mitzvos, it is proper that only his descendants are rewarded?! Perhaps it is because they had bad intent (refer to Bereishis 29:22:1:1,3, 29:22:151:1). Similarly, Balak brought Korbanos with bad intent (to 'merit' to curse Yisrael), and he was rewarded through a descendant (Nazir 23b; also refer to Bamidbar 23:1:1:3). - PF)
Why does it say "Gibor Chayil Metzora"?
Malbim: His Tzara'as was not due to illness. He was Gibor Chayil! The Tzara'as was a punishment. Chazal (Tanchuma Tazri'a 11) say that it was because troops of Aram captured a Jewish girl; she was under his authority.
