Lev Leviticus3. Mósebók, chapterkafli Book of LeviticusÞriðja Mósebók, chapterkafli 20

So make sure you observe the difference between clean and unclean animals and birds. Don't make yourselves unclean because of any animal or bird, or by anything that runs along the ground. I have made the difference clear: they are unclean for you.