Deuteronomy 27:2-6

2And on the day you cross over the Jordan to the land that the Lord your God is giving you, you shall set up large stones and plaster them with plaster.

3And you shall write on them all the words of this law, when you cross over to enter the land that the Lord your God is giving you, a land flowing with milk and honey, as the Lord, the God of your fathers, has promised you.

4And when you have crossed over the Jordan, you shall set up these stones, concerning which I command you today, on Mount Ebal, and you shall plaster them with plaster.

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,