Exodus 20:22-26

Then the LORD said to Moses, “Thus you shall say to the Israelites, ‘You have seen for yourselves that I have spoken to you from heaven. You shall not make other gods [to worship] besides Me; gods of silver or gods of gold, you shall not make [these lifeless idols] for yourselves. You shall make an altar of earth 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 recorded and remembered [through revelation of My divine nature] I will come to you and bless you. If you make an altar of stone for Me, you shall not build it of cut stones, for if you use a chisel on it, you will profane it. Nor shall you go up to My altar on steps, so that your nakedness will not be exposed on it.’