Jeremiah 6:28

“They are all grievous revolters, etc.] From the right way of God and his worship: or, they are all revolters of revoltersf149; of all, the greatest revolters, the greatest sinners and transgressors, the most stubborn and disobedient; or sons of revolters; fathers and children are alike. The Targum, is, “all their princes rebel;” and so the Vulgate Latin and Syriac versions: “walking with slanders”: of one another; or with deceit, as the Targum; in a hypocritical and fraudulent manner; playing the hypocrite with God, or tricking and deceiving their neighbours. They are “brass and iron”; as vile and mean as those metals, and not as gold and silver; or as hard and inflexible as they are; or…”

“grievous revolters--literally "contumacious of the contumacious," that is, most contumacious, the Hebrew mode of expressing a superlative. So "the strong among the mighty," that is, the strongest (Eze 32:21). See Jer 5:23; Hos 4:16. walking with slanders-- (Jer 9:4). "Going about for the purpose of slandering" [MAURER]. brass, &c.--that is, copper. It and "iron" being the baser and harder metals express the debased and obdurate character of the Jews (Isa 48:4; Isa 60:17).”

“6:28 The people’s dross was spiritual; it included rebellion against God, slander of other people, a hard and stubborn attitude, and a disposition to lead others into corruption (Ezek 22:18).”

“all grievous: Jer 5:23; Isa 1:5, Isa 31:6 walking: Jer 9:4, Jer 18:18, Jer 20:10; Psa 50:20 they are brass: Jer 6:30; Eze 22:18-22 corrupters: Isa 1:4; Rev 11:18, Rev 19:2 Jeremiah 6:29”

“Jer 6:28 gives a statement as to the moral character of the people. "Revolters of revolters" is a kind of superlative, and סרי is to be derived from סרר, not from סוּר, perverse of perverse; or, as Hitz., imitating the Heb. phrase, rebels of the rebellious. Going about as slanderers, see on Lev 19:16, in order to bring others into difficulties; cf. Eze 22:9. To this is subjoined the figurative expression: brass and iron, i.e., ignoble metal as contrasted with gold and silver, cf. Eze 22:18; and to this, again, the unfigurative statement: they are all dealing corruptingly. משׁחיתים, cf. Isa 1:4; Deu 31:29. There is no sufficient reason for joining כּלּם with the preceding: brass and iron, as…”