אלשיך
Alshekh on Torah, Numbers 25:4
Q — Why does the verse credit Pinchas with 'בקנאו את קנאתי' — using language of internal zeal — rather than 'בנקמו את נקמתי,' since what actually happened was a physical act of killing? Rashi (citing Maharal's elaboration) had to clarify that 'קנאה' here means 'נקמה,' because the praise must be for the deed itself.
A — The Alshich reads it in the opposite direction. The Torah deliberately did *not* say 'בנקמו'; the chiddush is that what 'השיב את חמתי' was specifically the קנאה — the inner kana'ut, the spiritual jealousy on behalf of Hashem — not the act of killing per se. Many could have grabbed a spear; not many would have done so out of the pure inner state Pinchas was in. The reward of brit shalom flows from kavanah, not from the body count.
וניישב לפי דרכנו אומרו 'בקנאו את קנאתי', כי הלא יקשה כי יותר מגדר קנאה עשה, כי גם פעל ועשה נקמה. כי על כן הוצרך רש"י ז"ל לומר, בנקמו את נקמתי. אך הוא לומר, כי [Cohen continues: Pinchas's reward stems not from the killing but from the inner קנאה / spiritual jealousy that animated it — the deed was a manifestation of an inner state, and that inner state is what 'returned Hashem's wrath.']