Rashi on Leviticus 18:3/רש"י על ויקרא י״ח:ג׳

1כמעשה ארץ מצרים AFTER THE DEEDS OF THE LAND OF EGYPT… [SHALL YE NOT DO] — This tells us that the deeds of the Egyptians and the Canaanites were more corrupt than those of all other nations, and that the district of Egypt in which the Israelites had resided (אשר ישבתם בה) was even more corrupt than all the rest of Egypt (Sifra, Acharei Mot, Section 8 3).

2אשר אני מביא אתכם שמה [AND AFTER THE DEEDS OF THE LAND OF CANAAN] WHITHER I BRING YOU [SHALL YE NOT DO] — This again tells us that those Canaanitish clans whom Israel subdued were more corrupt than all the others of them (Sifra, Acharei Mot, Section 8 4).

3ובחקתיהם לא תלכו NEITHER SHALL YE WALK IN THEIR ORDINANCES — What has Scripture left unsaid when it spoke of the deeds of the Egyptians and Canaanites that it felt compelled to add ובחקתיהם לא תלכו But by these latter words it refers to their social customs — things which have assumed for them the character of a law as, for instance, the frequenting of theaters and race-courses. Rabbi Meir, however, said: These (חקתיהם) refer to the "ways of the Amorites" (superstitious practices) which our Rabbis have enumerated (Shabbat 67a; Sifra, Acharei Mot, Section 8 8; cf. also Tosefta Shabbat 7).