Deuteronomy 27:4-7

So it shall be when you cross the Jordan, you shall set up on Mount Ebal, these stones, as I am commanding you today, and you shall coat them with lime. Moreover, you shall build there an altar to the LORD your God, an altar of stones; you shall not wield an iron tool on them. You shall build the altar of the LORD your God of uncut stones, and you shall offer on it burnt offerings to the LORD your God; and you shall sacrifice peace offerings and eat there, and rejoice before the LORD your God.