Joshua 4:6-7

4:6 The stones will be a reminder to you. When your children ask someday, ‘Why are these stones important to you?’ 4:7 tell them how the water of the Jordan stopped flowing before the ark of the covenant of the Lord. When it crossed the Jordan, the water of the Jordan stopped flowing. These stones will be a lasting memorial for the Israelites.”

Joshua 4:21

4:21 He told the Israelites, “When your children someday ask their fathers, ‘What do these stones represent?’