Adam Clarke on Exodus 23:32

Thou shalt make no covenant with them - They were incurable idolaters, and the cup of their iniquity was full. And had the Israelites contracted any alliance with them, either sacred or civil, they would have enticed them into their idolatries, to which the Jews were at all times most unhappily prone; and as God intended that they should be the preservers of the true religion till the coming of the Messiah, hence he strictly forbade them to tolerate idolatry.