וַיְהִ֤י יְהוָה֙ אֶתּ־יְהוּדָ֔ה וַיֹּ֖רֶשׁ אֶת־הָהָ֑ר כִּ֣י לֹ֤א לְהוֹרִישׁ֙ אֶת־יֹשְׁבֵ֣י הָעֵ֔מֶק כִּי־רֶ֥כֶב בַּרְזֶ֖ל לָהֶֽם׃
永恆者與猶大同在，猶大就奪得了山地；但他無法趕出平原的居民，因為他們有鐵車。
Rashi
However, he could not oust. [Targum] Yonasan interprets: Afterward, as they had sinned, they could not oust the valley dwellers.