Deuteronomy 27:4-8

4Therefore it shall be when ye have gone over Jordan, that ye shall set up these stones, which I command you this day, in mount Ebal, and thou shalt plaster them with plaster.

5And there shalt thou build an altar to the LORD thy God, an altar of stones: thou shalt not lift up any iron tool upon them.

6Thou shalt build the altar of the LORD thy God of whole stones: and thou shalt offer on it burnt offerings to the LORD thy God:

7And thou shalt offer peace offerings, and shalt eat there, and rejoice before the LORD thy God.

8And thou shalt write upon the stones all the words of this law very plainly.