וְהַיַּרְדֵּ֥ן יִגְבֹּל־אֹת֖וֹ לִפְאַת־קֵ֑דְמָה זֹ֡את נַחֲלַת֩ בְּנֵ֨י בִנְיָמִ֧ן לִגְבֽוּלֹתֶ֛יהָ סָבִ֖יב לְמִשְׁפְּחֹתָֽם׃
동방 경계는 요단이니 이는 베냐민 자손이 그 가족대로 얻은 기업의 사면 경계이었더라
Rashi on Joshua
The Jordan borders it on the east. The Jordan was the eastern boundary of Binyomin; as the Jordan goes along the width of his entire boundary to the east.