John Gill's Exposition of the Whole Bible
Jeremiah 6:21
Therefore thus saith the Lord,.... Because of their immorality and hypocrisy, their contempt of his word, and confidence in legal rites and ceremonies:
behold, I will lay stumblingblocks before this people; by which may be meant the judgments of God upon them, raising up enemies against them, and suffering them to invade their land; particularly the Assyrians, as the following words show. Moreover, the prophecies of the false prophets, and the doctrines which they were permitted to spread among the people, were snares and stumblingblocks unto them, they being given up to believe their lies, and to be hardened by them; nay, even true doctrines, the doctrines of justification and salvation by Christ, yea, Christ himself, were a rock of offence, and a stumbling stone to these people, Isaiah 8:14
and the fathers and the sons together shall fall upon them; or, "by them" z; the latter following the examples of the forager; and so it denotes, that as the corruption was general, the punishment would be:
and the neighbour and his friend shall perish; in the same calamity, being involved in the guilt of the same iniquity, in which they encouraged and hardened one another. The Septuagint and Arabic versions by "stumblingblocks" understand an "infirmity" or "disease", which should come upon the people, and make a general desolation among them. Kimchi interprets the whole of the wickedness of fathers and children, neighbours and friends, and such as were in trade and partnership, and of their delight in mischief; that though they were aware of the stumblingblocks, yet would not give each other warning of them. The whole, according to the accents, should be rendered thus, "and they shall fall upon them, the fathers and the sons together, the neighbour and his friend, and they shall perish"; falling and perishing are said of them all.
z בם "in iis", Schmidt; "in eis", Cocceius, Pegnanius.