And if you make Me an altar of stone, you shall not build it of hewn stone; for if you use your tool on it, you have profaned it.
Exodus 20:25
Surrounding context
20:24 An altar of earth you shall make 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 record My name I will come to you, and I will bless you.
20:25 And if you make Me an altar of stone, you shall not build it of hewn stone; for if you use your tool on it, you have profaned it.
20:26 Nor shall you go up by steps to My altar, that your nakedness may not be exposed on it.'