ועתה לך נא ארה לי. We learn from Balak inviting Bileam: "Now go and curse for me," how careful one has to be when one utters any words, even if one has no negative intention. Words have a habit of backfiring. Balak wound up cursing himself rather than Israel.

We have learned in Tractate Avot 5,22, that the disciples of the Patriarch Abraham are distinguished by possesssing a generous eye, a self-deprecating manner and a humble spirit, whereas a person of the opposite characteristics is sure to be a disciple of Bileam. The behavioral traits described in the tractate quoted reveal the character traits of envy, greed and egotism which are at the core of causing man's self-destruction.

חטאתי כי לא ידעתי . At first glance it seems strange that if Bileam was not aware of the angel's presence, (which had impeded the she-ass's progress), how he could have sinned. Man is responsible for ignorance of certain laws however, if they were the ones he should have known. Otherwise there would be no point in G–d equipping us with a brain. Bileam's mental faculties were such that he should have seen the angel. If even his ass could see the angel, his own lack of awareness could only be due to a sinful outlook on his part. Man is duty-bound to always be on guard not to be the cause of something sinful.

לא הביט און ביעקב . This is a reminder that even improper thoughts that have not surfaced, i.e. are "within Jacob," have not yet been translated into deeds, are frowned upon. We have elaborated elsewhere on this subject when we discussed the ten directives employed by G–d in creating the universe.