Exodus 20:24-26

20:24 ‘You must make for me an altar made of earth, and you will sacrifice on it your burnt offerings and your peace offerings, your sheep and your cattle. In every place where I cause my name to be honored I will come to you and I will bless you. 20:25 If you make me an altar of stone, you must not build it of stones shaped with tools, for if you use your tool on it you have defiled it. 20:26 And you must not go up by steps to my altar, so that your nakedness is not exposed.’