Rashi on Numbers 22:26/רש"י על במדבר כ״ב:כ״ו

1ויוסף 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).