Deuteronomy 27:2-6

2So it shall be on the day when you cross the Jordan to [enter] the land which the Lord your God gives you, that you shall set up for yourself large stones and coat them with plaster (lime, whitewash).

3You shall write on the stones all the words of this law when you cross over, so that you may go into the land which the Lord your God gives you, a land [of plenty] flowing with milk and honey, just as the Lord, the God of your fathers has promised you.

4Now when you cross the Jordan you shall set up these stones on Mount Ebal, just as I am commanding you today and coat them with plaster.

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;