וַיֹּסִ֙פוּ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל לַעֲשׂ֥וֹת הָרַ֖ע בְּעֵינֵ֣י יְהוָ֑ה וַיְחַזֵּ֨ק יְהוָ֜ה אֶת־עֶגְל֤וֹן מֶֽלֶךְ־מוֹאָב֙ עַל־יִשְׂרָאֵ֔ל עַ֛ל כִּֽי־עָשׂ֥וּ אֶת־הָרַ֖ע בְּעֵינֵ֥י יְהוָֽה׃
Metzudat David on Judges
AND HASHEM STRENGTHENED: They (Moabites) were weak, but Hashem strengthened them over Israel because of their evil actions.