Leviticus 20:25-26

Ye shall therefore put difference between clean beasts and unclean, and between unclean fowls and clean: and ye shall not make your souls abominable by beast, or by fowl, or by any manner of living thing that creepeth on the ground, which I have separated from you as unclean. And ye shall be holy unto me: for I the LORD am holy, and have severed you from other people, that ye should be mine.