Exodus 20:22-26

22And the LORD said to Moses, Thus thou shalt say to the children of Israel, Ye have seen that I have talked with you from heaven. 23Ye shall not make with me gods of silver, neither shall ye make to you gods of gold. 24An altar of earth thou shalt make to me, and shalt sacrifice on it thy burnt offerings, and thy peace offerings, thy sheep, and thy oxen: in all places where I record my name I will come to thee, and I will bless thee. 25And if thou wilt make me an altar of stone, thou shalt not build it of hewn stone: for if thou shalt lift up thy tool upon it, thou hast polluted it.1 26Neither shalt thou go up by steps to my altar, that thy nakedness be not discovered on it.