Deuteronomy 27:4-7

And it shall be, when ye are passed over the Jordan, that ye shall set up these stones, which I command you this day, in mount Ebal, and thou shalt plaster them with plaster. And there shalt thou build an altar unto Jehovah thy God, an altar of stones: thou shalt lift up no iron tool upon them. Thou shalt build the altar of Jehovah thy God of unhewn stones; and thou shalt offer burnt-offerings thereon unto Jehovah thy God: and thou shalt sacrifice peace-offerings, and shalt eat there; and thou shalt rejoice before Jehovah thy God.