וַיְהִ֤י יְהוָה֙ אֶתּ־יְהוּדָ֔ה וַיֹּ֖רֶשׁ אֶת־הָהָ֑ר כִּ֣י לֹ֤א לְהוֹרִישׁ֙ אֶת־יֹשְׁבֵ֣י הָעֵ֔מֶק כִּי־רֶ֥כֶב בַּרְזֶ֖ל לָהֶֽם׃
Yang Mahakekal menyertai Yehuda, sehingga ia menduduki daerah pegunungan; tetapi ia tidak dapat menghalau penduduk lembah, karena mereka mempunyai kereta perang besi.
Rashi
However, he could not oust. [Targum] Yonasan interprets: Afterward, as they had sinned, they could not oust the valley dwellers.