Matthew Henry on Jeremiah 9:1-11

Jeremiah wept much, yet wished he could weep more, that he might rouse the people to a due sense of the hand of God. But even the desert, without communion with God, through Christ Jesus, and the influences of the Holy Spirit, must be a place for temptation and evil; while, with these blessings, we may live in holiness in crowded cities. The people accustomed their tongues to lies. So false were they, that a brother could not be trusted. In trading and bargaining they said any thing for their own advantage, though they knew it to be false. But God marked their sin. Where no knowledge of God is, what good can be expected? He has many ways of turning a fruitful land into barrenness for the wickedness of those that dwell therein.