Rashi on Deuteronomy 14:2/רש"י על דברים י״ד:ב׳

1כי עם קדוש אתה FOR THOU ART AN HOLY PEOPLE — You are holy — your actual holiness comes to you from your fathers, but, in addition, ובך בחר ה׳ THE LORD HAS CHOSEN YOU [so that you are for two reasons bound to keep away from these pagan customs] (cf. Sifrei Devarim 97:1).