And there you shall build an altar to the LORD your God, an altar of stones. You shall wield no iron tool on them;
5 And there shalt thou build an altar. At their first entrance into the land, God commands that a sacrifice of thanksgiving should be offered to Him; and this Joshua performed, as is related in Joshua 8:30-31 "Then Joshua built an altar unto the Lord God of Israel in Mount Ebal; as Moses the servant of the Lord commanded the children of Israel, an altar...
Here is, I. A general charge to the people to keep God's commandments; for in vain did they know them, unless they would do them. This is pressed upon them, 1. With all authority. Moses with the elders of Israel, the rulers of each tribe (Deu 27:1), and again, Moses and the priests the Levites (Deu 27:9); so that the charge is given by Moses...
Commenting on Deuteronomy 27:1-10
And there shall thou build an altar to the Lord thy God,.... On the same mountain, though not of the same stones. Jarchi's note is,"after that (the setting up of the plastered stones) thou shalt bring from thence (from Jordan) others, and build of them an altar on Mount Ebal;''but Josephus (t) places this altar not on Mount Ebal, but between that and Gerizim.