Joshua 4:21-23

Then he said to Bnei-Yisrael saying, “When your children ask their fathers in time to come saying: ‘What are these stones?’ then you will inform your children saying, ‘Israel crossed this Jordan on dry ground.’ For ADONAI your God dried up the waters of Jordan before you until you crossed—just as ADONAI your God did to the Sea of Reeds, which He dried up before us until we crossed over