רמב"ן — הוא אשר דבר ה' לאמר בקרבי אקדש

Q — After Nadav and Avihu die, Moshe tells Aharon: 'הוא אשר דבר ה' לאמר בקרבי אקדש ועל פני כל העם אכבד.' Where had Hashem ever said this? Rashi: the verse 'ונקדשתי בכבודי' in Tetzaveh, read as 'בִּמכובדי' (through My honored ones). Ibn Ezra: an oral statement Moshe received but the Torah didn't record.

A — Ramban: neither. The root דב"ר doesn't always mean explicit speech. It can mean 'gezera and machshava' — decree and thought. So: 'דברתי אני עם לבי' (Kohelet), 'וזה הדבר אשר מל יהושע' (= 'this matter'), 'על דבר הכסף' (= 'concerning the silver'), 'כאשר דבר ה'' (= as Hashem decreed). On Ramban's reading, Moshe is saying: this terrible event is the realization of Hashem's decree-in-itself — 'אשר גזר ה' לאמר אל לבו' — that 'בקרבי אקדש' through any prikha against His kedusha, and 'אכבד' through everyone's reverence in the mishkan. No prior speech is needed.