Joshua 4:17 (KJV)

And the children of Reuben, and the children of Gad, and half the tribe of Manasseh, passed over armed before the children of Israel, as Moses spake unto them:

About forty thousand prepared for war passed over before the LORD unto battle, to the plains of Jericho.

On that day the LORD magnified Joshua in the sight of all Israel; and they feared him, as they feared Moses, all the days of his life.

And the LORD spake unto Joshua, saying,

Command the priests that bear the ark of the testimony, that they come up out of Jordan.

And it came to pass, when the priests that bare the ark of the covenant of the LORD were come up out of the midst of Jordan, and the soles of the priests' feet were lifted up unto the dry land, that the waters of Jordan returned unto their place, and flowed over all his banks, as they did before.

And the people came up out of Jordan on the tenth day of the first month, and encamped in Gilgal, in the east border of Jericho.

And those twelve stones, which they took out of Jordan, did Joshua pitch in Gilgal.

And he spake unto the children of Israel, saying, When your children shall ask their fathers in time to come, saying, What mean these stones?

Then ye shall let your children know, saying, Israel came over this Jordan on dry land.