Judges 12:5-6

5The Gileadites captured the fords of the Jordan opposite Ephraim. So when any of the fugitives of Ephraim said, “Let me cross over,” the men of Gilead would ask him, “Are you an Ephraimite?” If he said, “No,”

6then they would say to him, “Say now, ‘Shibboleth,’” and he said “Sibboleth” since he could not pronounce it right, then they would seize him and slay him at the fords of the Jordan. At that time 42,000 of Ephraim fell.