Isaiah 54:9 (King James Bible) for this is as the waters of Noah unto me
The King James Bible has the words is as in italics, which means that these words were supplied by the King James translators and are not found in the Hebrew. The Book of Mormon is also missing these two words.
The Book of Mormon text is definitely difficult to process here. Nonetheless, words in italics in the King James Bible are often missing when a passage is quoted in the Book of Mormon. In particular, see the discussion under 2 Nephi 13:14 regarding the frequent omission of the italicized is in the long quotation from Isaiah 2–14. Here in 3 Nephi 22:9 we have the only case where is as is lacking in the Book of Mormon text. Even so, the critical text will follow the shorter Book of Mormon reading since it appears to be fully intended. The 1830 typesetter placed a comma between the initial “for this” and the following “the waters of Noah unto me”, which helps facilitate the processing of this difficult reading.
Summary: Maintain in 3 Nephi 22:9 the awkward but original “for this / the waters of Noah unto me”; this reading more closely follows the Hebrew in Isaiah 54:9; the King James text has is as in italics after “for this”.