Commentary for Numbers 22:26

ויוסף מלאך ה' עובר AND THE ANGEL OF THE LORD WENT FURTHER — went further in front of him — it went on so as to be before him in another spot. It is similar to, (Genesis 33:3) “And he passed in front of them”. — And there is a Midrashic explanation in Tanchuma: What reason had he to stand in three places? He (the Angel) showed him (Balaam) symbols referring to the three patriarchs (Midrash Tanchuma, Balak 8).

אשר אין דרך לנטות ימין ושמאל, “where there was no room to turn right or left.” This needs to be understood allegorically, [I suppose because both the words “right” and “left” are superfluous. Ed.] The words are understood as referring to people who veer theologically to the ‘right’ or ‘left, i.e. Avraham and Yitzchok each had a son who did not follow in his father’s footsteps. By the time Yaakov appeared on the scene of history all his children followed in his footsteps. The descriptions of the ability of the ass to pass the angel in the first two instances, though with difficulty, and not without discomfort to its owner, were to be a message to Bileam that by now there was no loophole in the conduct of the descendants of Avraham that would allow him room for his curse to be effective.

To place himself before him in a different place. Rashi is answering the question: The word עבור ["passed"] is only appropriate where one crosses a river or between two objects, but here we do not find that [Bil'am] passed through anything. Therefore he explains that עבור here means “[passed] before him” as if to say that he went to another place to stand before him. The reason why Rashi stated לעבור ["to pass"] instead of עבור ["passed"] is that this is the rule of the root עבר that it comes with a lamed. Re’m.