The Gileadites captured the fords of the Jordan leading to Ephraim, and whenever a fugitive from Ephraim would say, "Let me cross over," the Gileadites would ask him, "Are you an Ephraimite?" If he answered, "No,"

Judges 3:28
"Follow me," he told them, "for the LORD has delivered your enemies the Moabites into your hand." So they followed him down and seized the fords of the Jordan leading to Moab, and did not allow anyone to cross over.

Judges 12:4
Jephthah then gathered all the men of Gilead and fought against Ephraim. And the men of Gilead struck them down because the Ephraimites had said, "You Gileadites are fugitives in Ephraim, living in the territories of Ephraim and Manasseh."

Judges 12:6
they told him, "Please say Shibboleth." If he said, "Sibboleth," because he could not pronounce it correctly, they seized him and killed him at the fords of the Jordan. So at that time 42,000 Ephraimites were killed.

And the Gileadites took the passages of Jordan before the Ephraimites: and it was so, that when those Ephraimites which were escaped said, Let me go over; that the men of Gilead said to him, Are you an Ephraimite? If he said, No;