The first instance of a chiasmus found in the Book of Mormon, as currently arranged, is in 1 Nephi. However, it’s important to note that the detection of chiastic structures can be subjective and dependent on interpretation. One example could be the following from 1 Nephi 1:8-10:
1. (A) And being thus overcome with the Spirit, he was carried away in a vision, even that he saw
– (B) the heavens open,
– (C) and he thought he saw God sitting upon his throne,
surrounded with numberless concourses of angels
in the attitude of singing and praising their God.
– (D) And it came to pass that he saw
– (E) One descending out of the midst of heaven,
– (F) and he beheld that his luster was above that of the sun at noon-day.
– (F’) And he also saw twelve others following him,
and their brightness did exceed that of the stars in the firmament.
– (E’) And they came down and went forth upon the face of the earth;
– (D’) and the first came and
– (C’) stood before my father, and gave unto him a book, and bade him that he should read.
– (B’) And as he read, he was filled with the Spirit of the Lord.
2. (A’) And he read, saying: Wo, wo, unto Jerusalem, for I have seen thine abominations! Yea, and many things did my father read concerning Jerusalem—that it should be destroyed, and the inhabitants thereof; many should perish by the sword, and many should be carried away captive into Babylon.
It’s important to note that these structures can be subjective and can vary depending on the interpretation of the text. Some readers might find other chiastic structures in the same text or disagree about whether this example qualifies as a chiasmus.