Adapted From Based On What's Bothering Rashi:
Bamidbar 31:8 is where we’re told that Bilam is killed. Rashi says that Bilam tried to get Bnei Yisrael by using their weapon of the mouth – so he was “gotten” through the means usually employed by the Umot HaOlam – the sword. What pshat oriented purpose does this medrash serve that prompted Rashi to put it in his peirush?
The Nefesh HaGer points out that throughout all of Tanach there is an amazing Mesorah that lasted over a thousand years while tanach was written which employed the following code: Whenever non-Jewish nations attack The Jews (or other nations) the expression used is hargu bacherev. An example of this is Edom saying, "Lest with a sword (bacherev) I will approach you." – Bamidbar 20:18. When the Jews attack the nothern nations the expression used is hargu lefi cherev. (See Bamidbar 20:18 and Shmot 17:13).
The phrase Pi Cherev, on a superficial level, reflects that the sword is similar to a mouth. The mouth cuts (into foods like meat) and the sword cuts flesh/meat. A deeper meaning is that when Jews attack physically the component of prayer is always present. We see this first from Yaakov as he faces war with eisav. Rashi on Breishit 32:10 states that Yakov prepared 3 things before his confrontation with Eisav; gifts, prayer and battle. Yaakov, despite getting ready for a physical fight made sure to include the element of prayer. Similarly, Moshe raised his hands in prayer in the battle against Amalek.
When Jews fight it is with a double edged sword; the actual blade and the prayer which sharpens the blade.
Nechama Leibowitz tells us that children are taught (and hold on to the fact) that Bilam was the mastermind behind the plan to seduce the Jewish men into idolatry. Parshat Matot (31:16) - הֵן הֵנָּה הָיוּ לִבְנֵי יִשְׂרָאֵל, בִּדְבַר בִּלְעָם, לִמְסָר-מַעַל בַּיהוָה, עַל-דְּבַר-פְּעוֹר; וַתְּהִי הַמַּגֵּפָה, בַּעֲדַת יְהוָה - Behold, these caused the children of Israel, through the counsel of Balaam, to revolt so as to break faith with the L-rd in the matter of Peor, and so the plague was among the congregation of the L-rd (Machon Mamre traslation) is where the Torah reveales that it was Bilam's counsel that led to this tragedy. When the event is first describes, as it transpires, in Parshat Balak the people are blamed 25:1) וַיֵּשֶׁב יִשְׂרָאֵל, בַּשִּׁטִּים; וַיָּחֶל הָעָם, לִזְנוֹת אֶל-בְּנוֹת מוֹאָב - "And Israel abode in Shittim, and the people began to commit harlotry with the daughters of Moab." Shadal explains fills in the rest of the story, saying that on his way back to Aram Bilam passed through Midyan and heard the Israelites had sinned and worshipped idols through being involved with Bnot Moav. He then took this reality and ran with it upon realizing it was the only way to get at Bnei Yisrael. He advised the Midianites to send their women to lure Bnei Yisrael becuase this was the only way Bnei Yisrael would sin and forfeit God’s protection.
Nechama suggests that the reason for this spacing is to make clear that the people did what they did by choice. The Torah is blocking the option of passing responsibility off onto anyone else. As she puts it (in an English adaptation by Aryeh Newman), "The moral responsibility ultimately rested on the Israelites themselves. They were guilty."
This is a critical lesson. may we be blessed to integrate this kind of ethical responsibility into our lives.