2 Peter 2:16

Whenever a person rejects God’s Word and will, he or she begins to act irrationally because God’s Word reveals true reality. Finally right becomes wrong, and wrong becomes right for him or her. That is what happened to Balaam. He became so insensitive that God had to use a dumb animal to rebuke him. The ancients regarded animals as mute (dumb) because they did not speak human language. [Note: Bauckham, p. 268.] That donkey, a proverbially obstinate animal, was wiser than Balaam (cf. Judges 11).

"It is sufficient to say to one who believes at all in miracles, that it was no more difficult for God to utter thought through the mouth of the ass in the words of men, than to stop men, as he once did, from talking in a given language and cause them to talk in another." [Note: Nathaniel M. Williams, "Commentary on the Epistles of Peter," in An American Commentary on the New Testament, p. 102.]