Why does it say "b'Aznai Hashem Tzevakos"?
Rashi, from Targum Yonasan: The Navi says, my two ears heard when Hashem decreed the following on them, and with a Shevu'ah.
Radak: Hashem says so. What you speak among yourselves, and agree to rob the poor, it rose to My ears, for I am the Master of legions above and below, and I can lower and raise.
Malbim: Hashem swore in His great name.
Why does it say "Im Lo"?
Radak: This is an expression of a Shevu'ah. The same applies to "Im Lo Ka'asher Dimisi Ken Haysah" (14:24), "Im Lo Shivisi v'Domamti" (Tehilim 131:2). This is like one who says 'this will not be if this will not be.'
Why does it say "Rabim"?
Radak: This is like "Rabei ha'Melech" (Yirmeyah 41:1). They are esteemed and built nicely. This is like "Gedolim v'Tovim"; the matter is repeated in different words.
Malbim: They were not desolate because they were small or inferior. They were "Gedolim v'Tovim"!
What is the significance of the houses being desolate?
Radak: You thought that you alone will dwell in the land - I say that you will be exiled from them, and your houses, which were many and great, will be desolate without residents.
Why does it say "me'Ein Yoshev"?
Malbim: This is why the houses will be desolate - half the city will be exiled. Therefore, in vain you steal the Oni's house to increase your houses! Had you stolen fields and vineyards, you would have gained!