Commentaire sur Les Nombres 25:6

והנה איש וגו׳ AND BEHOLD, ONE [OF THE CHILDREN OF ISRAEL CAME] The tribe of Simeon gathered to Zimri who was their prince, saying to him. “We are sentenced to death and you remain quiet!?”, — as it is related in the chapter beginning אלו הן הנשרפין (Sanhedrin 82a).

ויקרב אל אחיו, in order to seduce her, in violation of Leviticus 18,6 that revealing private parts of members of the opposite sex is also forbidden.

ויקרב אל אחיו את המדינית, “He brought the Midianite woman near to his brethren;” the Torah really should have written: “a man by the name of Zimri, prince of the tribe of Shimon, went and brought the Midianite woman whose name was Cozbi bat Tzur near his brethren.” However, the Torah could not bring itself to reveal name of the wicked person who had become the reason for the raging pestilence until he had been dealt with, i.e. until Pinchas had killed him and until Pinchas had received his reward. Only then does the Torah mention the names of both the man and the woman involved (verses 14-15). All of this is to tell us the praises of Pinchas who displayed fearlessness. Although the people in question were a prince and a king’s daughter respectively, he did not let this stop him from killing them (Rashi).