וַיַּנַּ֤ח יְהוָה֙ אֶת־הַגּוֹיִ֣ם הָאֵ֔לֶּה לְבִלְתִּ֥י הוֹרִישָׁ֖ם מַהֵ֑ר וְלֹ֥א נְתָנָ֖ם בְּיַד־יְהוֹשֻֽׁעַ׃ (פ)
So the LORD left those nations, without driving them out hastily; neither delivered He them into the hand of Joshua.
Read midrashic interpretation of Judges 2:23: and classical rabbinic exegesis.