Joshua 4:4-9

So Joshua called together the twelve men he had chosen—one from each of the tribes of Israel. He told them, “Go into the middle of the Jordan, in front of the Ark of the LORD your God. Each of you must pick up one stone and carry it out on your shoulder—twelve stones in all, one for each of the twelve tribes of Israel. We will use these stones to build a memorial. In the future your children will ask you, ‘What do these stones mean?’ Then you can tell them, ‘They remind us that the Jordan River stopped flowing when the Ark of the LORD’s Covenant went across.’ These stones will stand as a memorial among the people of Israel forever.” So the men did as Joshua had commanded them. They took twelve stones from the middle of the Jordan River, one for each tribe, just as the LORD had told Joshua. They carried them to the place where they camped for the night and constructed the memorial there. Joshua also set up another pile of twelve stones in the middle of the Jordan, at the place where the priests who carried the Ark of the Covenant were standing. And they are there to this day.