Deuteronomy 27:5-10

5And there you shall build an altar to the Lord your God, an altar of stones. You shall wield no iron tool on them;

6you shall build an altar to the Lord your God of uncut stones. And you shall offer burnt offerings on it to the Lord your God,

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

8And you shall write on the stones all the words of this law very plainly."

9Then Moses and the Levitical priests said to all Israel, "Keep silence and hear, O Israel: this day you have become the people of the Lord your God.

10You shall therefore obey the voice of the Lord your God, keeping his commandments and his statutes, which I command you today."