Chur & The Golden Calf

The reason the text does not refer explicitly to the killing of Chur is so that this murder should not remain a permanent memory for all future generations. Hashem's is protective of the good reputation of the Jewish people, and the only reason He recorded the details of the sin of the golden calf is so that if a community would commit a collective sin in the future they would have the encouragement to repent using the fact that Hashem forgave the Jewish people the sin of the golden calf as proof that their repentance too would be accepted by Him.

(Ohr HaChaim)