Judges 12:5-6

Jephthah 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,” they 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.