Deuteronomy 27:5-10

5And there shalt thou build an altar unto Jehovah thy God, an altar of stones: thou shalt lift up no iron tool upon them. 6Thou shalt build the altar of Jehovah thy God of unhewn stones; and thou shalt offer burnt-offerings thereon unto Jehovah thy God: 7and thou shalt sacrifice peace-offerings, and shalt eat there; and thou shalt rejoice before Jehovah thy God. 8And thou shalt write upon the stones all the words of this law very plainly.

9And Moses and the priests the Levites spake unto all Israel, saying, Keep silence, and hearken, O Israel: This day thou art become the people of Jehovah thy God. 10Thou shalt therefore obey the voice of Jehovah thy God, and do his commandments and his statutes, which I command thee this day.