Deuteronomy 27:4-6

Amplified Bible

⁴ Now when you cross the Jordan you shall set up these stones on Mount Ebal, just as I am commanding you today and coat them with plaster. ⁵ There you shall build an altar to the Lord your God, an altar of stones; you shall not use an iron tool on them. ⁶ You shall build the altar of the Lord your God with whole [uncut] stones, and offer burnt offerings on it to the Lord your God;