1)
Why does it say "Zos Lahem..."?
1.
Malbim: Even though they have three severe sins - idolatry, Arayos and murder - their punishment will be for reviling Yisrael. This is like "Al Sheloshah Pish'ei Mo'av...", "Al Sheloshah Pish'ei Bnei Amon v'Al Arba'ah Lo Ashivenu" (Amos 2:1, 1:13).
