The Mouth Is Under Control
“G-d opened the mouth of the donkey” (Numbers 22:28) — The miracle served to warn Balaam not to follow divination and sorcery, nor to curse Israel. Just as G-d can open the mouths of the mute, so too can He silence those who speak, or put other words in their mouths, so they speak according to His will. (Ramban)
A Miraculous Wonder
“G-d opened the mouth of the donkey” (Numbers 22:28) — Just as the donkey is not naturally a speaking creature and only spoke by divine decree, so too Balaam, though he uttered lofty prophecies about the end of days, did so not by his own power or merit, but through a miraculous wonder. (Rabbi Yitzchak Isaac of Komarna)
Ignorance as Sin
“Balaam said to the angel of G-d: I have sinned, for I did not know...” (Numbers 22:34) — Rabbi Chaim of Sanz once asked a certain Rabbi why he showed no concern for the difficult plight of a fellow townsperson. The Rabbi replied that he hadn’t known about it. Rabbi Chaim said: “Regarding Balaam it says, ‘I have sinned for I did not know.’ This teaches that not knowing is itself a sin.”
Returned as Before
“Balaam arose, went and returned home, and Balak went on his way” (Numbers 24:25) — This verse highlights the depth of their wickedness. Even though Balaam saw in prophecy the greatness of Israel, and Balak heard it all, they still went back to their wicked ways as before, without taking the lesson to heart. (Korban HaAni)