3 Then you must inscribe on them all the words of this law when you cross over, so that you may enter the land the Lord your God is giving you, a land flowing with milk and honey just as the Lord, the God of your ancestors, said to you. 4 So when you cross the Jordan you must erect on Mount Ebal these stones about which I am commanding you today, and you must cover them with plaster. 5 Then you must build an altar there to the Lord your God, an altar of stones—do not use an iron tool on them. 6 You must build the altar of the Lord your God with whole stones and offer burnt offerings on it to the Lord your God. 7 Also you must offer fellowship offerings and eat them there, rejoicing before the Lord your God.
29 He hung the king of Ai on a tree, leaving him exposed until evening. At sunset Joshua ordered that his corpse be taken down from the tree. They threw it down at the entrance of the city gate and erected over it a large pile of stones (it remains to this very day). 30 Then Joshua built an altar for the Lord God of Israel on Mount Ebal, 31 just as Moses the Lord’s servant had commanded the Israelites. As described in the law scroll of Moses, it was made with uncut stones untouched by an iron tool. On it they offered burnt sacrifices to the Lord and sacrificed tokens of peace. 32 There, in the presence of the Israelites, Joshua inscribed on the stones a duplicate of the law written by Moses.
Notes and References
"... Hebrew hereb could be properly translated 'sword,' but here, as Ibn Ezra suggested, hereb is the name of a tool used for stone cutting. In Deuteronomy 27:5, 'an altar of stones, do not wield barzel, "iron", over them,' barzel cannot refer to iron in some general way and most reasonably refers to the same type of tool (compare also Joshua 8:31). The shape of the tool most likely determined its name: 'they will beat their swords (harbotam) into pruning hooks' (ittim) (Isaiah 2:4; Micah 4:3). The harbot surim, 'flint swords,' of Joshua 5:2-3 were not weapons of war but hand implements for circumcision; compare also Exodus 4:25; Exodus 20:25, as in Ezekiel 26:9 ..."
Zevit, Ziony The Religions of Ancient Israel: A Synthesis of Parallactic Approaches (p. 277) Continuum, 2001