Joshua 4:4-7

So Joshua summoned the twelve men he had selected from the Israelites, one man for each tribe, and said to them, “Go across to the ark of the LORD your God in the middle of the Jordan. Each of you lift a stone onto his shoulder, one for each of the Israelite tribes, so that this will be a sign among you. In the future, when your children ask you, ‘What do these stones mean to you? ’ you should tell them, ‘The water of the Jordan was cut off in front of the ark of the LORD’s covenant. When it crossed the Jordan, the Jordan’s water was cut off.’ Therefore these stones will always be a memorial for the Israelites.”