The sin of Judah - Idolatry.

Is written with a pen of iron - It is deeply and indelibly written in their heart, and shall be as indelibly written in their punishment. Writing with the point of a diamond must refer to glass, or some vitrified substance, as it is distinguished here from engraving with a steel burine, or graver. Their altars show what the deities are which they worship. There may be reference here to the different methods of recording events in those days: -

1. A pen or stile of iron, for engraving on lead or wood.

2. A point of a diamond, for writing on vitreous substances.

3. Writing on tables of brass or copper.

4. Writing on the horns of the altars the names of the deities worshipped there. This is probable.

In several parts of India, and all through Ceylon, an iron or steel pen is used universally; with these the natives form the letters by incisions on the outer rind of the palm leaf. Books written in this way are very durable. This pen is broad at the top, has a very fine sharp point, and is sharp at one side as a knife, to shave and prepare the palm leaf. A pen of this description now lies before me.

written.

Job 19:23,24 Oh that my words were now written! oh that they were printed in a book!...

point. Heb. nail. graven.

Proverbs 3:3 Let not mercy and truth forsake you: bind them about your neck; write them on the table of your heart:

Proverbs 7:3 Bind them on your fingers, write them on the table of your heart.

2 Corinthians 3:3 For as much as you are manifestly declared to be the letter of Christ ministered by us, written not with ink...

and upon.

Leviticus 4:17,18,25 And the priest shall dip his finger in some of the blood, and sprinkle it seven times before the LORD, even before the veil...

Hosea 12:11 Is there iniquity in Gilead? surely they are vanity: they sacrifice bullocks in Gilgal; yes...

The Heath in the Desert and the Tree by the River
'He shall be like the heath in the desert, and shall not see when good cometh; but shall inhabit the parched places in the wilderness, a salt land and not inhabited...He shall be as a tree planted by the waters, and that spreadeth out her roots by the river, and shall not see when heat cometh, but her leaf shall be green; and shall not be careful in the year of drought, neither shall cease from yielding fruit.'--JER. xvii. 6, 8. The prophet here puts before us two highly finished pictures. In the …
Alexander Maclaren—Expositions of Holy Scripture

"For what the Law could not Do, in that it was Weak through the Flesh, God Sending his Own Son in the Likeness of Sinful Flesh,
Rom. viii. 3.--"For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin condemned sin in the flesh." For what purpose do we meet thus together? I would we knew it,--then it might be to some better purpose. In all other things we are rational, and do nothing of moment without some end and purpose. But, alas! in this matter of greatest moment, our going about divine ordinances, we have scarce any distinct or deliberate …
Hugh Binning—The Works of the Rev. Hugh Binning

Appendix xvii. The Ordinances and Law of the Sabbath as Laid Down in the Mishnah and the Jerusalem Talmud.
The terribly exaggerated views of the Rabbis, and their endless, burdensome rules about the Sabbath may best be learned from a brief analysis of the Mishnah, as further explained and enlarged in the Jerusalem Talmud. [6476] For this purpose a brief analysis of what is, confessedly, one of the most difficult tractates may here be given. The Mishnic tractate Sabbath stands at the head of twelve tractates which together from the second of the six sections into which the Mishnah is divided, and which …
Alfred Edersheim—The Life and Times of Jesus the Messiah