Joshua 4:6-7

61Let this be a sign among you, so that 2when your children ask 3later, saying, ‘What do these stones mean to you?’ 7then you shall say to them, ‘Because the 4waters 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 5memorial to the sons of Israel forever.”