Rashi on Deuteronomy 12:22/רש"י על דברים י״ב:כ״ב

1אך כאשר יאכל את הצבי וגו׳ BUT ONLY AS THE GAZELLE [AND THE HART] IS EATEN, [SO THOU SHALT EAT THEM] — i.e. thou art not admonished to eat them in a state of cleanness as is the case with sacrifices which you slaughter in a holy place; if, however, you will argue: How is the case with the gazelle and the hart? Their fat is permitted as food; so, too, is the fat of non-consecrated domestic animals (חולין) permitted! Then I reply: Scripture says אך (which word has a limitative force and thus indicates that חולין are not to be treated like the gazelle and the hart in every respect) (cf. Bekhorot 15a).