Judges 12:4-6

4The people of Ephraim responded, “You men of Gilead are nothing more than fugitives from Ephraim and Manasseh.” So Jephthah gathered all the men of Gilead and attacked the men of Ephraim and defeated them.

5Jephthah captured the shallow crossings of the Jordan River, and whenever a fugitive from Ephraim tried to go back across, the men of Gilead would challenge him. “Are you a member of the tribe of Ephraim?” they would ask. If the man said, “No, I’m not,”

6they would tell him to say “Shibboleth.” If he was from Ephraim, he would say “Sibboleth,” because people from Ephraim cannot pronounce the word correctly. Then they would take him and kill him at the shallow crossings of the Jordan. In all, 42,000 Ephraimites were killed at that time.