Exodus 20:22-26

22And the Lord said to Moses, "Thus you shall say to the people of Israel: 'You have seen for yourselves that I have talked with you from heaven.

23You shall not make gods of silver to be with me, nor shall you make for yourselves gods of gold.

24An altar of earth you shall make for me and 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.

25If you make me an altar of stone, you shall not build it of hewn stones, for if you wield your tool on it you profane it.

26And you shall not go up by steps to my altar, that your nakedness be not exposed on it.'