Exodus 20:24-26

“Make an altar of dirt for me, and sacrifice on it your whole burnt offerings and fellowship offerings, your sheep and your cattle. Worship me in every place that I choose, and I will come and bless you. If you use stones to make an altar for me, don’t use stones that you have shaped with tools. When you use any tools on them, you make them unsuitable for use in worship. And you must not go up to my altar on steps, or people will be able to see under your clothes.”