Deuteronomy 27:4-7

Therefore it shall be, when you have crossed over the Jordan, that on Mount Ebal you shall set up these stones, which I command you today, and you shall whitewash them with lime. And there you shall build an altar to the LORD your God, an altar of stones; you shall not use an iron tool on them. You shall build with whole stones the altar of the LORD your God, and offer burnt offerings on it to the LORD your God. You shall offer peace offerings, and shall eat there, and rejoice before the LORD your God.