Deuteronomy 27:5-10

5Moreover, you are to build there an altar to the LORD your God, an altar of stones. You must not use any iron tool on them. 6You shall build the altar of the LORD your God with uncut stones and offer upon it burnt offerings to the LORD your God. 7There you are to sacrifice your peace offerings, eating them and rejoicing in the presence of the LORD your God. 8And you shall write distinctly upon these stones all the words of this law.”

9Then Moses and the Levitical priests spoke to all Israel: “Be silent, O Israel, and listen! This day you have become the people of the LORD your God. 10You shall therefore obey the voice of the LORD your God and follow His commandments and statutes I am giving you today.”