Judges 2:3

Wherefore I also said, through the mouth of Joshua, Joshua 23:13, I will not drive them out from before you, as a punishment of their disobedience, but they shall be as thorns in your sides, and their gods shall be a snare unto you, Exodus 23:33. "Israel, in the conquest, has acted like a slothful gardener. It has not thoroughly destroyed the thorns and thistles of its fields. The consequence will be that sowing and planting and other field labors will soon be rendered painful by the presence of spiteful thorns. What will turn the Canaanites into stinging weeds and snares for Israel? The influence of habitual intercourse. Familiarity blunts aversion, smoothes away contrarieties, removes differences, impairs obedience. It induces forgetfulness of what one was, what one promised, and to what conditions one is subject. Familiar intercourse with idolaters will weaken Israel's faith in the invisible God. " (Lange.)