Exodus 20:22-26 - Instructions For Building Altars
22 And Jehovah will say to Moses, Thus shalt thou say to the sons of Israel, Ye saw that from the heavens I spake with you. 23 Ye shall not make to me gods of silver, and gods of gold ye shall not make to yourselves.
24 An altar of earth shalt thou make to me, and sacrifice upon it thy burnt-offering and thy peace, and thy sheep and thy cattle: and in every place where I shall cause my name to be remembered, I will come to thee and bless thee. 25 And if thou shalt make to me an altar of stones, thou shalt not build them, cutting, for didst thou lift up thy sword upon it, and thou shalt defile it. 26 And thou shalt not go up by steps upon mine altar, that thou shalt not uncover thy nakedness upon it