Toldot

Chapter 28;v.5

פרוש רש”י : אם יעקב ועשו. אני יודע מה מלמדנו

This is one of the places where Rashi writes that he does not know what it teaches us.
The other place with similar Rashi’s comment is found in Exodus, Parashat Mishpatim, Chapter 22;v.28.