Leviticus 20:25-26

Therefore you are to distinguish the clean animal from the unclean one, and the unclean bird from the clean one. Do not become contaminated  by any land animal, bird, or whatever crawls on the ground; I have set these apart as unclean for you.  You are to be holy to me because I, the Lord, am holy, and I have set you apart from the nations to be mine.