Complete Commentary on the Whole Bible, by Matthew Henry, at sacred-texts.com
(Jer 9:1-11) The people are corrected, Jerusalem is destroyed.
(Jer 9:12-22) The captives suffer in a foreign land.
(Jer 9:23-26) God's loving-kindness, He threatens the enemies of his people.
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.
In Zion the voice of joy and praise used to be heard, while the people kept close to God; but sin has altered the sound, it is now the voice of lamentation. Unhumbled hearts lament their calamity, but not their sin, which is the cause of it. Let the doors be shut ever so fast, death steals upon us. It enters the palaces of princes and great men, though stately, strongly built, and guarded. Nor are those more safe that are abroad; death cuts off even the children from without, and the young men from the streets. Hearken to the word of the Lord, and mourn with godly sorrow. This alone can bring true comfort; and it can turn the heaviest afflictions into precious mercies.
In this world of sin and sorrow, ending soon in death and judgement, how foolish for men to glory in their knowledge, health, strength, riches, or in any thing which leaves them under the dominion of sin and the wrath of God! and of which an account must hereafter be rendered; it will but increase their misery. Those are the true Israel who worship God in the Spirit, rejoice in Christ Jesus, and have no confidence in the flesh. Let us prize the distinction which comes from God, and will last for ever. Let us seek it diligently.