Judges 12:5-6

5The men of Gilead captured the shallow crossings of the Jordan River leading back to Ephraim. Whenever a fugitive from Ephraim said, “Let me cross,” the men of Gilead would ask, “Are you from Ephraim?” If he answered, “No,”

6they would tell him, “Say the word shibboleth.” If the fugitive would say sibboleth, because he couldn’t pronounce the word correctly, they would grab him and kill him at the shallow crossings of the Jordan River. At that time 42,000 men from Ephraim died.