Leviticus 20:25-26

You are therefore to make a distinction between the clean animal and the unclean, and between the unclean bird and the clean; and you shall not make yourselves detestable by animal or by bird, or by anything that crawls on the ground, which I have distinguished for you as unclean. So you are to be holy to Me, for I the Lord am holy; and I have singled you out from the peoples to be Mine.