וַיֹּ֣אמְר֔וּ יְרֻשַּׁ֥ת פְּלֵיטָ֖ה לְבִנְיָמִ֑ן וְלֹֽא־יִמָּחֶ֥ה שֵׁ֖בֶט מִיִּשְׂרָאֵֽל׃
And they said: ‘They that are escaped must be as an inheritance for Benjamin, that a tribe be not blotted out from Israel.
Read midrashic interpretation of Judges 21:17: and classical rabbinic exegesis.