Why does it say "Ani Yadati"?
Radak: I know that [Mo'av's] Sheker said amidst pride will not be fulfilled. The evil will come on them!
Malbim: I punished Mo'av because I know their hatred of Yisrael.
What is the meaning of "Evraso v'Lo Chen"?
Rashi: Their hatred for Yisrael is not justified.
Radak #1: Mo'av's hatred for its Nochri neighbors is without reason, only due to its pride.
Radak #2: Mo'av's anger [what they wanted to do amidst anger] was not fulfilled. "Chen" is true, like "Ken Bnos Tzlafchad Dovros" (Bamidbar 27:7).
What are "Badav"?
Rashi: [Mo'av's] Giborim.
Radak: [Mo'av's] words of Sheker 1 . It said amidst pride 'I will do so and so.' They will not be fulfilled 2 .
Malbim: [Mo'av's] thoughts.
Radak (Yeshayah 16:6): Badav is like "Cherev El ha'Badim v'No'alu" (50:36).
Radak: ["V'Lo] Chen" applies to Badav, even though the Trup (note) on "Chen" is Asnachta (which ends the first matter in the verse, like a semicolon). Also Yonason translated like this, and so it is in Yeshayah (16:5. The Asnachta is under "David", yet "David" applies also to the end of the verse. - PF) We can explain also like the Trup; "v'Lo Chen" applies to "Evraso" (refer to 48:30:2:1-3).
Why does it say "Lo Chen Asu"?
Rashi: They did not return to the seed of Avraham like [what he] bestowed to them. He fought the [four] kings, and saved their patriarch Lot!
Radak: Bnei Mo'av did not do like they intended.
Malbim: They did not flee.