JDG 12:6

6 they would say to him, “Say the word ‘Shibboleth’.” The men of Ephraim could not pronounce that word correctly. So if the person from the tribe of Ephraim said ‘Sibboleth’, [they would know that he was lying and that he was really from the tribe of Ephraim, and] they would kill him there at the ford. So the men of Gilead killed 42,000 people from the tribe of Ephraim at that time.