שופטים, פרק י״ב, פסוק ה׳

Following the defeat of the tribe of Ephraim in battle, the conflict shifted into a tactical blockade. The victors aimed to cut off all escape routes and prevent the fleeing soldiers from returning safely to their land. To accomplish this, the men of Gilead stationed guards at the strategic crossing points along the Jordan River [רש״י, מצודת דוד, ביאור שטיינזלץ].

When the surviving Ephraimites who had escaped the fighting reached the river and attempted to cross, they faced strict interrogation. This questioning was primarily directed at the ordinary members of the tribe. The prominent and well-known figures of Ephraim were instantly recognized by the guards upon arrival, making any interrogation of them entirely unnecessary [מצודת דוד].

As each unknown traveler approached the riverbank, the guards asked a direct question to determine their specific tribal affiliation, asking if they belonged to the tribe of Ephraim [רד״ק]. Fully aware that revealing their true identity would place their lives in immediate danger, the desperate fugitives would naturally deny their roots and claim they did not [ביאור שטיינזלץ].