Deuteronomy 27:4-7

And when you have crossed the Jordan, set up these stones on Mount Ebal, as I command you today, and coat them with plaster. Build there an altar to the LORD your God, an altar of stones. Do not use any iron tool on them. Build the altar of the LORD your God with fieldstones and offer burnt offerings on it to the LORD your God. Sacrifice fellowship offerings there, eating them and rejoicing in the presence of the LORD your God.