Rashi on Numbers 19:2/רש"י על במדבר י״ט:ב׳

1וזאת חקת התורה THIS IS THE ORDINANCE OF THE LAW — Because Satan and the nations of the world taunt Israel, saying, “What is this command and what reason is there for it”, on this account it (Scripture) writes (uses) the term חקה about it, implying: It is an enactment from before Me; you have no right to criticize it (Yoma 67b; cf. Midrash Tanchuma, Chukat 7).

2ויקחו אליך THEY SHALL TAKE UNTO THEE — It will always be called by thy name: people will speak of the cow which Moses prepared in the wilderness (Midrash Tanchuma, Chukat 8).

3אדמה תמימה [A COW] RED, PERFECT — This means that it should be perfect in respect to its redness (Sifrei Bamidbar 123:1), — so that if there are two black hairs in it (or two of any color other than red) it is unfitted for the rite here described (Mishnah Parah 2:5).