Jeremiah 17:1

There is much arguing amongst those that are critical about the true signification of words, what is here signified by שטיד which we translate a diamond; most agree that it doth not signify a diamond, (not used in engraving,) but that by the pen of iron, and the point of a diamond, are meant some tools with which they were wont to engrave things upon hard substances; it may be made in a figure resembling the claw of a bird, as the word seemeth to import.

It is graven upon the table of their heart; it is graven in their hearts; they are so accustomed to sin, so inured to idolatry, that there is no hope of any reclaiming them. For how can they that are accustomed to do evil, do well?

And upon the horns of your altars; nor is it a thing done in secret, but it is written, or painted, or engraven upon the horns of their altars. God’s altar was foursquare, and at each corner there was a rising part made of brass something high, these were called the horns of the altar. See Exodus 27:2; Ezekiel 43:15,Ezekiel 43:16. Now their sin is either said to be engraven or published upon the horns of the altar, because the blood of the sacrifices which they offered to idols was sprinkled there, or because their altars had some inscription upon them, declaring to what idol that altar was consecrated, as the altar of Athens had.