They made their hearts as an adamant stone. They made their hearts as hard as a stone which could receive no cutting or engraving; no message from God could find entrance; and this from their wilful obstinacy.
The word rendered "adamant," shamir, probably means "diamond," a stone so hard, says Jerome, as to break all metals to pieces, but to be itself broken by none; hence it is called adamas, "unconquerable."
Ezekiel (Ezekiel 3:9) notes that it is harder than flint (comp. Jeremiah 17:1). The LXX; paraphrasing, gives. τὴν καρδίαν αὐτῶν ἔταξαν ἀπειθῆ, "They set their heart disobedient." The Law. The various enactments of the Mosaic system.
In his Spirit; rather, by his Spirit. The leaching which the Spirit of God inspired the prophets to deliver (comp. Nehemiah 9:30; 2 Kings 17:13; Micah 3:8). And for the succession of prophets from Solomon to the Captivity, see note on Amos 2:11; and to those there enumerated, add Iddo, Shemaiah, Hanani, Micaiah, Huldah.