Deuteronomy 4:15-18

So keep watch on yourselves with care; for you saw no form of any sort on the day when the voice of the Lord came to you in Horeb out of the heart of the fire: So that you may not be turned to evil ways and make for yourselves an image in the form of any living thing, male or female, Or any beast of the earth, or winged bird of the air, Or of anything which goes flat on the earth, or any fish in the water under the earth.