Exodus 20:22-26

Then the LORD said to Moses, “Thus you shall say to the sons of Israel, ‘You yourselves have seen that I have spoken to you from heaven. You shall not make other gods besides Me; gods of silver or gods of gold, you shall not make for yourselves. 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. 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. And you shall not go up by steps to My altar, so that your nakedness will not be exposed on it.’