וַיִּקְבֹּ֤ץ יִפְתָּח֙ אֶת־כָּל־אַנְשֵׁ֣י גִלְעָ֔ד וַיִּלָּ֖חֶם אֶת־אֶפְרָ֑יִם וַיַּכּוּ֩ אַנְשֵׁ֨י גִלְעָ֜ד אֶת־אֶפְרַ֗יִם כִּ֤י אָמְרוּ֙ פְּלִיטֵ֤י אֶפְרַ֙יִם֙ אַתֶּ֔ם גִּלְעָ֕ד בְּת֥וֹךְ אֶפְרַ֖יִם בְּת֥וֹךְ מְנַשֶּֽׁה׃
Then Jephthah gathered together all the men of Gilead, and fought with Ephraim; and the men of Gilead smote Ephraim, because they said: ‘Ye are fugitives of Ephraim, ye Gileadites, in the midst of Ephraim, and in the midst of Manasseh.’
Read halakhic rulings (Jewish law) on Judges 12:4: and classical halakhic sources.