Deuteronomy 27:5-10

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. 9And Moses and the priests the Levites spoke to all Israel, saying, Take heed, and hearken, O Israel; this day thou art become the people of the LORD thy God. 10Thou shalt therefore obey the voice of the LORD thy God, and do his commandments and his statutes, which I command thee this day.