Judges 12:6

they would say, “Say the word ‘Shibboleth.’” The men of Ephraim could not say that word correctly. They pronounced the word “Sibboleth.” So if the man said, “Sibboleth,” then the men of Gilead knew he was from Ephraim. So they would kill him at the crossing place. They killed 42,000 men from Ephraim.