Judges 12:4-6

4Then Jephthah gathered together all the men of Gilead, and fought with Ephraim: and the men of Gilead smote Ephraim, because they said, Ye Gileadites are fugitives of Ephraim among the Ephraimites, and among the Manassites.

5And the Gileadites took the fords of Jordan before the Ephraimites: and it was so, that when those Ephraimites who had escaped said, Let me go over; that the men of Gilead said to him, Art thou an Ephraimite? If he said, Nay;

6Then said they to him, Say now Shibboleth: and he said Sibboleth: for he could not frame to pronounce it right. Then they took him, and slew him at the fords of Jordan: and there fell at that time of the Ephraimites forty and two thousand.