Read Exodus 20:25 Using Other Translations
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.
If you make me an altar of stone, you shall not build it of hewn stones, for if you wield your tool on it you profane it.
If you use stones to build my altar, use only natural, uncut stones. Do not shape the stones with a tool, for that would make the altar unfit for holy use.