Joshua 4:6-7

⁶Let this be a sign among you, so that when your children ask later, saying, ‘What do these stones mean to you?’ ⁷then you shall say to them, ‘Because the waters of the Jordan were cut off before the ark of the covenant of the Lord; when it crossed the Jordan, the waters of the Jordan were cut off.’ So these stones shall become a memorial to the sons of Israel forever.”