Job 19:24

With a pen of iron and lead -- For ever in a rock they may be hewn.

Jeremiah 17:1

The sin of Judah is written with a pen of iron, With the point of a diamond, Graven on the tablet of their heart, And on the horns of your altars,

Exodus 28:11-12

the work of an engraver in stone, openings of a signet, thou dost open the two stones by the names of the sons of Israel; turned round, embroidered with gold, thou dost make them.

Exodus 28:21

and the stones are according to the names of the sons of Israel, twelve, according to their names, openings of a signet, each by his name are they for the twelve tribes.

Exodus 32:16

and the tables are the work of God, and the writing is the writing of God, graven on the tables.

Deuteronomy 27:2-3

and it hath been, in the day that ye pass over the Jordan unto the land which Jehovah thy God is giving to thee, that thou hast raised up for thee great stones, and plaistered them with plaister,

Deuteronomy 27:8

and written on the stones all the words of this law, well engraved.'

Treasury of Scripture Knowledge

Summary

That they were graven with an iron pen and lead in the rock for ever!

General references

Bible References

Graven

Exodus 28:11
the work of an engraver in stone, openings of a signet, thou dost open the two stones by the names of the sons of Israel; turned round, embroidered with gold, thou dost make them.
Exodus 32:16
and the tables are the work of God, and the writing is the writing of God, graven on the tables.
Deuteronomy 27:2
and it hath been, in the day that ye pass over the Jordan unto the land which Jehovah thy God is giving to thee, that thou hast raised up for thee great stones, and plaistered them with plaister,
Jeremiah 17:1
The sin of Judah is written with a pen of iron, With the point of a diamond, Graven on the tablet of their heart, And on the horns of your altars,

General references

Deuteronomy 6:9
and thou hast written them on door-posts of thy house, and on thy gates.
Jeremiah 30:2
'Thus spake Jehovah, God of Israel, saying, Write for thee all the words that I have spoken unto thee on a book.