Fewer Words Version: The Gileadites crossed the Jordan River before the Ephraimites.
When the Ephraimites came to the river, the men of Gilead said to them, "Are you an Ephraimite?"
If they said, "No", then they said to him, "Say "Shibboleth".
And they said, "Sibboleth", because they couldn't pronounce it correctly.
So the Gileadites killed 42,000 Ephraimites who were trying to cross the Jordan. Judges 12:5-6