Shaarei Yosher, sec. 2: Qedushah – part 1
In my opinion, this whole concept is included in Hashem’s mitzvah “Be holy, [for I am Holy].” The Midrash (Leviticus, Emor, ch. 24) says about this verse: “Can it [truly] be ‘Like Me?’ This is why it continues, ‘for I am Holy’ to teach that My Sanctity is above yours.” ולדעתי כל ענין זה נכלל במצות ה׳ של “קדושים תהיו”,...