Exodus 20:24 - 20:26
24 You shall make an altar of earth for Me, and you shall sacrifice on it your burnt offerings and your peace offerings, your sheep and your oxen; in every place where I cause My name to be remembered, I will come to you and bless you. 25 And if you make an altar of stone for Me, you shall not build it of cut stones, for if you wield your tool on it, you will profane it. 26 And you shall not go up by steps to My altar, so that your nakedness will not be exposed on it.’