Joshua 4:21-23

21He said to the Israelites, “In the future when your descendants ask their parents, ‘What do these stones mean?’ 22tell them, ‘Israel crossed the Jordan on dry ground.’ 23For the LORD your God dried up the Jordan before you until you had crossed over. The LORD your God did to the Jordan what he had done to the Red Sea Or the Sea of Reeds when he dried it up before us until we had crossed over.