Rashi on Numbers 15:23/רש"י על במדבר ט״ו:כ״ג

1את כל אשר צוה וגו׳ EVEN ALL THAT [THE LORD] HATH COMMANDED [YOU] etc. — This tells us that he who acknowledges the divinity of an idol is like one who denies the Torah in its entirety and all that the prophets prophesied, because it states, “[and if yo have erred and not done … all that the Lord hath commanded by Moses] from the day that the Lord commanded (Moses), and hence forth [throughout all your generations]” (cf. Sifrei Bamidbar 111:1).