Deuteronomy 27:4-8 NIV

[4] And when you have crossed the Jordan, set up these stones on Mount Ebal, as I command you today, and coat them with plaster. [5] Build there an altar to the LORD your God, an altar of stones. Do not use any iron tool on them. [6] Build the altar of the LORD your God with fieldstones and offer burnt offerings on it to the LORD your God. [7] Sacrifice fellowship offerings there, eating them and rejoicing in the presence of the LORD your God. [8] And you shall write very clearly all the words of this law on these stones you have set up.”