Rashi on Numbers 18:10/רש"י על במדבר י״ח:י׳

1בקדש הקדשים תאכלנו וגו׳ IN THE MOST HOLY PLACE THOU SHALT EAT IT etc. — This teaches with reference to the sacrifices holy in the highest degree that they must be eaten only in the fore-court and only by male priests (cf. Sifrei Bamidbar 117:2).