Deuteronomy 27:5 KJV
And there shalt thou build an altar unto the Lord thy God, an altar of stones: thou shalt not lift up any iron tool upon them.
Deuteronomy 27:5, King James Version
In context
4 Therefore it shall be when ye be gone over Jordan, that ye shall set up these stones, which I command you this day, in mount Ebal, and thou shalt plaister them with plaister.
5 And there shalt thou build an altar unto the Lord thy God, an altar of stones: thou shalt not lift up any iron tool upon them.
6 Thou shalt build the altar of the Lord thy God of whole stones: and thou shalt offer burnt offerings thereon unto the Lord thy God: