Exodus 20:25 in the King James Version
And if thou wilt make me an altar of stone, thou shalt not build it of hewn stone: for if thou lift up thy tool upon it, thou hast polluted it.
Context
24 You shall make an altar of earth for me, and shall sacrifice on it your burnt offerings and your peace offerings, your sheep and your cattle. In every place where I record my name I will come to you and I will bless you.
25 If you make me an altar of stone, you shall not build it of cut stones; for if you lift up your tool on it, you have polluted it.
26 You shall not go up by steps to my altar, that your nakedness may not be exposed to it.’