Joshua 4:5-9

4:5 Joshua told them, “Go in front of the ark of the Lord your God to the middle of the Jordan. Each of you is to put a stone on his shoulder, according to the number of the Israelite tribes. 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.”

4:8 The Israelites did just as Joshua commanded. They picked up twelve stones, according to the number of the Israelite tribes, from the middle of the Jordan as the Lord had instructed Joshua. They carried them over with them to the camp and put them there. 4:9 Joshua also set up twelve stones in the middle of the Jordan in the very place where the priests carrying the ark of the covenant stood. They remain there to this very day.

Joshua 4:20-24

4:20 Now Joshua set up in Gilgal the twelve stones they had taken from the Jordan. 4:21 He told the Israelites, “When your children someday ask their fathers, ‘What do these stones represent?’ 4:22 explain to your children, ‘Israel crossed the Jordan River on dry ground.’ 4:23 For the Lord your God dried up the water of the Jordan before you while you crossed over. It was just like when the Lord your God dried up the Red Sea before us while we crossed it. 4:24 He has done this so all the nations of the earth might recognize the Lord’s power and so you might always obey the Lord your God.”