Notwithstanding several carefully articulated arguments, vv. 9b–10
exist in three Hebrew witnesses (MT 4QIsaa 4QIsab) plus
LXX Syr Vulg; 1QIsaa remains the sole witness that omits vss. 9b–10;
the other witnesses, including two from Qumran (4QIsaa 4QIsab,
although note that the texts of these copies of Isaiah are fragmented), include
vv. 9b–10. And furthermore, the Greek text features a significant plus at the
end of v. 10 (ὅταν ἀναστῇ θραῦσαι τὴν γῆν, “when he rises to crush the earth”),
a plus that was evidently assimilated from v. 19. After carefully weighing the
evidence, some critics maintain that 1QIsaa did indeed accidently
drop this long passage while copying the text. Although the mechanism for
dropping it is not immediately apparent, it is my considered view that the
scribe or one dictating the text inadvertently omitted a full (horizontal) line
of text from the Vorlage. Forty-five characters are missing from 1QIsaa,
just slightly above the average of 43–44 characters per line for this column. (Donald
W. Parry, Exploring the Isaiah Scrolls and Their Textual Variants [Supplements
to the Textual History of the Bible 3; Leiden, Brill: 2020], 49-50)