Judges 12:4-6

4Then Jephthah gathered all the men of Gilead and fought with Ephraim. And the men of Gilead struck Ephraim, because they said, "You are fugitives of Ephraim, you Gileadites, in the midst of Ephraim and Manasseh."

5And the Gileadites captured the fords of the Jordan against the Ephraimites. And when any of the fugitives of Ephraim said, "Let me go over," the men of Gilead said to him, "Are you an Ephraimite?" When he said, "No,"

6they said to him, "Then say Shibboleth," and he said, "Sibboleth," for he could not pronounce it right. Then they seized him and slaughtered him at the fords of the Jordan. At that time 42,000 of the Ephraimites fell.