What is a "Keluv"?
Rashi citing Targum Yonasan: It is a [coop] in which birds are fattened. Radak - it is made of boards. This is like "v'Hinei Keluv Kayitz" (Amos 8:1).
Why did they say "Al Ken Gadlu va'Ya'ashiru"?
Radak: Because the money came without exertion, they increased property and became rich.
Malbim: They did not become rich via toil, rather, Al Ken - via all this murder.
QUESTIONS ON RASHI
Rashi writes that Keluv is a coop in which birds are fattened. Why this a metaphor for the Resha'im's houses?
Radak: Just like they fill a coop with as many birds as it can hold, and put in it food and drink and they eat there constantly, so the Resha'im's houses are full of scheming, i.e. money obtained via scheming, and they indulge in it.
Malbim: Just like a trapper fills a coop with the many birds that he trapped, so they filled their houses with money that they stole.
