Judges 3:2-4

2He left those nations simply because he wanted to teach the subsequent generations of Israelites, who had not experienced the earlier battles, how to conduct holy war.

3These were the nations: the five lords of the Philistines, all the Canaanites, the Sidonians, and the Hivites living in Mount Lebanon, from Mount Baal Hermon to Lebo-Hamath.

4They were left to test Israel, so the Lord would know if his people would obey the commands he gave their ancestors through Moses.