Charles Ellicott Commentary Judges 21:17

"And they said, There must be an inheritance for them that are escaped of Benjamin, that a tribe be not blotted out from Israel." — Judges 21:17 (ASV)

There must be an inheritance. — Rather, possession of the remnant shall be for Benjamin — that is, we will leave untouched their land and possessions. “We give you leave to take the whole land of Benjamin to yourselves” (Josephus, Antiquities V, Chapter 3, Section 12).

That a tribe be not destroyed. — Benjamin never quite recovered this crushing blow. Even though it furnished the second judge (Ehud) and the first king (Saul) to Israel, and was advantageously situated, and was often honoured by the residence of Samuel, it became a mere satellite to the more powerful tribe of Judah. Perhaps in the quiescence and permanence derived from the close association with its powerful neighbour we see in part the fulfilment of the blessing in Deuteronomy 33:12.