Judges 12:5-6

5And Gilead took the fords of the Jordan before Ephraim; and it came to pass that when the fugitives of Ephraim said, Let me go over, the men of Gilead said to him, Art thou an Ephraimite? and he said, No.

6Then they said to him, Say now Shibboleth! and he said, Sibboleth, and did not manage to pronounce [it] rightly. Then they took him, and slaughtered him at the fords of the Jordan. And there fell at that time of Ephraim forty-two thousand.