Judges 12:5-6

In order to keep the Ephraimites from escaping, the Gileadites captured the places where the Jordan could be crossed. When any Ephraimite who was trying to escape would ask permission to cross, the men of Gilead would ask, “Are you an Ephraimite?” If he said, “No,” they would tell him to say “Shibboleth.” But he would say “Sibboleth,” because he could not pronounce it correctly. Then they would grab him and kill him there at one of the Jordan River crossings. At that time forty-two thousand of the Ephraimites were killed.