Deuteronomy 27:5-10

5There you shall build an altar to the Lord your God, an altar of stones; you shall not use an iron tool on them.

6You shall build the altar of the Lord your God with whole [uncut] stones, and offer burnt offerings on it to the Lord your God;

7and you shall sacrifice peace offerings and shall eat there, and shall rejoice before the Lord your God.

8And you shall write very clearly on the stones all the words of this law.”

9Then Moses and the Levitical priests said to all Israel, “Be silent and listen, O Israel! This day you have become a people for the Lord your God.

10So you shall obey the voice of the Lord your God, and do His commandments and statutes which I am commanding you today.”