6 so that this may be a sign among you. When your children ask in time to come, "What do those stones mean to you?' 7 then you shall tell them that the waters of the Jordan were cut off in front of the ark of the covenant of the Lord. When it crossed over the Jordan, the waters of the Jordan were cut off. So these stones shall be to the Israelites a memorial forever." 8 The Israelites did as Joshua commanded. They took up twelve stones out of the middle of the Jordan, according to the number of the tribes of the Israelites, as the Lord told Joshua, carried them over with them to the place where they camped, and laid them down there.
Matthew Henry's Commentary on Joshua 4:6-8
Commentary on Joshua 4:1-9
(Read Joshua 4:1-9)
The works of the Lord are so worthy of rememberance, and the heart of man is so prone to forget them, that various methods are needful to refresh our memories, for the glory of God, our advantage, and that of our children. God gave orders for preparing this memorial.