Joshua 4:1-9 NIV
When the whole nation had finished crossing the Jordan, the LORD said to Joshua, “Choose twelve men from among the people, one from each tribe, and tell them to take up twelve stones from the middle of the Jordan, from right where the priests are standing, and carry them over with you and put them down at the place where you stay tonight.” So Joshua called together the twelve men he had appointed from the Israelites, one from each tribe, and said to them, “Go over before the ark of the LORD your God into the middle of the Jordan. Each of you is to take up a stone on his shoulder, according to the number of the tribes of the Israelites, to serve as a sign among you. In the future, when your children ask you, ‘What do these stones mean?’ tell them that the flow of the Jordan was cut off before the ark of the covenant of the LORD. When it crossed the Jordan, the waters of the Jordan were cut off. These stones are to be a memorial to the people of Israel forever.” So the Israelites did as Joshua commanded them. They took twelve stones from the middle of the Jordan, according to the number of the tribes of the Israelites, as the LORD had told Joshua; and they carried them over with them to their camp, where they put them down. Joshua set up the twelve stones that had been in the middle of the Jordan at the spot where the priests who carried the ark of the covenant had stood. And they are there to this day.