Why does it say "Im Ganavim Ba'u Lecha"?
Rashi: Thieves came upon you.
Radak: People who saw the Churban of Edom will be astonished. What happened to you?! If thieves plundered you at night when you were sleeping, and you did not sense them to stop them and rise against them...
Malbim: After beginning the Nevu'ah of what will happen to Edom in the end of days, it returns to say what will happen before that. Enemies came to its land and plundered it. I explained (Yirmeyah Perek 49) that Edom's Anshei Briso enticed it to go to war outside its border, against its neighbors. When it went out, the enemy came and totally destroyed Edom. [The enemy] is compared to thieves who come at night, when the owner is unaware.
Why does it say "Eich Nidmeisah"?
Rashi, Targum Yonasan: Why did you sleep until they stole all that they wanted?
Radak: How were you cut off? This is like "Nidmu Ami mi'Bli ha'Da'as" (Hoshe'a 4:6).
Why does it say "Im Shodedei Laylah"?
Malbim: It is even more astounding how you could sleep when night plunderers came. They make more noise than thieves!
What is the meaning of "ha'Lo Yignevu Dayam"?
Radak: Thieves normally steal what suffices for them, i.e. what they can carry, and leave the rest!
Malbim: They will steal as much as they want. Why didn't you waken from your sleep to expel them?!
Why does it say "Im Botzrim Ba'u Lach ha'Lo Yash'iru Olelos"?
Rashi: People who harvest, they leave Olelos. These [who will plunder Edom] will be leave anything! They will search you and reveal, and investigate your hidden matters.
Radak: If plunderers came upon you during the day, like harvesters who harvest a vineyard and return time after time to harvest, like it says "Hahsev Yadcha k'Votzer Al Salsilos" (Yirmeyah 6:9), it is impossible that they would not leave Olelos (deficient clusters), which are not seen due to their small size. They are hidden under vine leaves. How were you searched, that the plunderers did not leave to you anything, even hidden matters?! Botzrim is like a repetition of thieves, just most thieves come at night.
Malbim: Thieves who reap, they come to a field when the owner is not there. They leave Olelos, for they fear lest the owner come, and do not harvest everything.